401 - GENERAL CONCRETE 400-4 When used, add silica fume with other cementitious materials during batching procedures. If the silica fume cannot be added to the cementitious materials, add th e loose silica fume to the bo ttom of the stationary drum that is wet, but has no standing water, before adding the dry materials. The Engineer may approve shreddable bags on a performance basis, only when a central batch mixing process is used. If so, add the bags to half of the mixing water and mix before adding cementitious materials, aggregate and remainder of water. Mix silica fume modified concrete for a minimum of 100 mixing revolutions.
7.Submit complete mix design data including proportions and sources of all mix ingredients, and the results of strength tests representing the mixes proposed for use. The strength data may come from previous KDOT project records or from a laboratory regularly inspected by Cement and Concrete Reference Laboratory (CCRL), and shall equal or exceed the strength requirements for the Grade sp ecified in the Contract Documents as determined by subsection 401.3b . Perform compressive strengt h tests according to KT-76.
e.Strength. Design concrete to meet TABLE 401-3 . TABLE 401-3: CONCRETE STRENGTH REQUIREMENTS Specified 28 Day Compressive Strengths, minimum, psi f’c Grade of Concrete: Non Air Entrained/Air Entrained Concrete Grade 7.0 7,000 Grade 6.0 6,000 Grade 5.0 5,000 Grade 4.5 4,500 Grade 4.0 4,000 Grade 3.5 3,500 Grade 3.0 3,000 Grade 2.5 2,500
f.High Early Strength Concrete. Design the high early strength concrete mix to comply with strength and time requirements specified in the Contract Documents. Unless otherwise specified, design high early strength concrete for pavement at a minimum of 1 of the Contractor’s standard deviations above 2400 psi (cylinders) at 24 hours. Submit complete mix design data including proportions and sources of all mix ingredients, and the results of time and strength tests representing the mixes proposed for us e. The strength and time data may come from previous KDOT project records or from an independe nt laboratory, and shall equal or ex ceed the strength and time requirements listed in the Contract Documents.
g.Slump. Designate a slump for each concrete mix design th at is required for satisfactory placement of the concrete application not to exceed 5 inches except wh ere controlled by maximum allowable slumps stated in SECTIONS 402, 403 and 404 . Reject concrete with a slump that limits the workability or placement of the concrete.
h.Permeability. Except for Structural Concrete as shown in SECTION 402 , supply a concrete with either a maximum 28 day Volume of Permeable Voids of 12.0% as per KT-73, a minimum 28 day surface resistivity of 9.0 kΩ-cm as per KT-79, or a maximum 56 day Rapid Chloride Permeability of 3,000 Coulombs as per AASHTO T- 277. The field verification test procedure must be the same test procedure as the mix design approval test.
i.Admixtures for Acceleration, Ai r-Entraining, Plastici zing, Set Retardation and Water Reduction. Verify that the admixtures used are compatible and will wo rk as intended without detrimental effects. Use the dosages recommended by the admixture manufacturers. Incorporate and mix the admixtures into the concrete mixtures according to the manufacturer’s recommendations. Determin e the quantity of each admixture for the concrete mix design. The Engineer will allow minor adjustments to the dose rate of admixtures to compensate for environmental changes during placement without a new concrete mix design or trial batch. 401 - GENERAL CONCRETE 400-5 Redosing is permitted to control slump or air content in the field, when approved by the Engineer, time and temperature limits are not ex ceeded, and at least 30 mixing revolutions rema in before redosing. Redose according to manufacturer’s recommendations. If another admixture is added to an air-entrained concrete mixture, determine if it is necessary to adjust the air-entraining admixture dosage to maintain the specified air content.
1.Accelerating Admixture. When speci fied in the Contract Documents, or in situations that involve contact with reinforcing steel and require early strength development to expedite opening to traffic, a non-chloride accelerator may be approved. The Engineer may approve the use of a Type C or E accelerating admixture. A Grade 2 calcium chloride accelerator may be used when patching an existing pavement more than 10 years old. Add the calcium chloride by solution (the solution is considered part of the mixing water). For a minimum cure of 4 hours at 60°F or above, use 2% (by dry we ight of cement) calcium chloride. For a minimum cure of 6 hours at 60°F or above, use 1% (by dry we ight of cement) calcium chloride.
2.Air-Entraining Admixture. When specified, use an air-entraining admixture in the concrete mixture.
3.Water-Reducers and Set-Retarders. If unfavorable weat her or other conditions adversely affect the placing and finishing properties of the concrete mix, the Engineer may allow the use of water-reducers and set-retarders. Verify that the admixtures will work as intended without de trimental effects. If the Engineer approves the use of water- reducers and set-retarders, their continue d use depends on their performance. If at any point, a water-reducer is used to produce a slump equal to or greater than 7 ½ inches, comply with subsection 401.3g .
4.Plasticizer Admixture. A plasticizer is defined as an admixture that produces flowing concrete, without further addition of water, and/or retards the setting of concrete. Flowing concrete is defined as having a slump equal to or greater than 7 ½ inches while maintaining a cohesive nature. Include a batching sequence in the concrete mix design. Consider the location of the concrete plant in relation to the job site, and identify when and at what location the wate r reducer or plasticizer is added to the concrete mixture. Manufacturers of plasticizers may recommend mixing revolutions beyond the limits specified in subsection 401.8 . If necessary, address the additional mixing revolutions in the concrete mix design. The Engineer may allow up to 60 additional revolutions when plastici zers are designated in the mix design. Before the concrete mixture with a slump equal to or greater than 7 ½ inches is used on the project, conduct tests on at least 1 full trial batch of the concrete mix design in the presence of the Engin eer to determine the adequacy of the dosage and the batching sequence of the plasticizer to obtain the desired properties. Determine the air content of the trial batch both before and after the addition of the plasticizer. Monitor the slump, air content, temperature and workability at regular intervals of the time period from when the plasticizer is added until the estimated time of completed placement. At the discretion of the Engineer, if all the properties of the trial batch remain within the specified limits, the trial batc h may be used in the project. Do not add water after plasticizer is added to the concrete mixture. 401.4 REQUIREMENTS FO R COMBINED MATERIALS
a.Measurements for Prop ortioning Materials.
1.Cement. Measure cement as packed by the manufactur er. A sack of cement is considered as 0.04 cubic yards weighing 94 pounds net. Measur e bulk cement by weight. In either case, the measurement must be accurate to within 0.5% throughout the range of use.
2.Supplemental Cementitious Materials. Supplemental cementitious materials proportioning and batching equipment is subject to the same controls as required fo r cement. Provide positive cut off with no leakage from the cut off valve. Cementitious materials may be weighed accumulatively with the cement or separately. If weighed accumulatively, weigh the cement first.
3.Water. Measure the mixing wa ter by weight or by volume accurate to within 1% th roughout the range of use.
4.Aggregates. Measure the aggreg ates by weight, accurate to within 0.5% throughout the range of use.
5.Admixtures. Measure liquid admi xtures by weight or volume, accurate to with in 3% of the quantity required. If liquid admixtures are used in small quantities in proportion to the cement as in the case of air-entraining agents, use readily adjustable mechanical dispensing equipment capable of being set to deliver the required quantity and to cut off the flow automatically when this quantity is discharged. 401 - GENERAL CONCRETE 400-6
b.Testing of Aggregates.
1.Production of On Grade Concrete Aggregate (OGC A). If OGCA is required, notify the Engineer in writing at least 2 weeks in advance of producing the aggreg ate. Include the source of the aggregate and the date production will begin. Failure to notify the Engineer, as required, may result in rejection of the aggregate for use as OGCA. Maintain separate stockpiles for OGCA at the quarry and at the batch site and identify them accordingly.
2.Testing Aggregates at the Batch Site. Provide th e Engineer with reasonable facilities at the batch site for obtaining samples of the aggregates. Provide adequate a nd safe laboratory facilities at the batch site allowing the Engineer to test the aggregates for co mpliance with the specified requirements. KDOT will sample and test aggregat es from each source to determine th eir compliance with specifications. Do not batch the concrete mixture until the Engineer has determined that the aggregates comply with the specifications. KDOT will conduct sampling at the batchi ng site, and test samples according to the Sampling and Testing Frequency Chart in Part V. For QC/QA contracts, establish testing intervals within the specified minimum frequency. After initial testing is complete, and the Engineer has determined that the aggregate process control is satisfactory, use the aggregates concurrently with sampling and testing as long as tests verify compliance with specifications. When batching, sample the aggregates as n ear the point of batching as feasible. Sample from the stream as the storage bins or weigh hoppers are loaded. If samples cannot be taken from the stream, take them from approved stockpiles, or use a template and sample from the co nveyor belt. If test results indicate an aggregate does not comply with specifications, cease concrete production using that aggregate. Unless a tested and approved stockpile for that aggregate is available at the batch plan t, do not use any additional ag gregate from that source and specified grading until subsequent testing of that aggregat e indicate compliance with specifications. When tests are completed and the Engineer is satisfied that process control is satisfactory, production of concrete using aggregates tested concurrently with production may resume.
c.Handling of Materials.
1.Approved stockpiles are permitted only at the batch plant and only for small concrete placements or for maintaining concrete production. Mark the approved stockpile with an "Approved Materials" sign. Provide a suitable stockpile area at the batch pl ant so that aggregates are stored without detrimental segregation or contamination. At the plant, limit stockpiles of tested and approved coarse, fine and intermediate aggregate to 250 tons each, unless approved for more by the Engineer. If mixed aggregate is used, limit the approved stockpile to 500 tons, the size of each being proportional to the amount of each aggregate to be used in the mix. Load aggregates into the mixer such that no materi al foreign to the concrete or material capable of changing the desired proportions is included.
2.Segregation. Do not use segreg ated aggregates. Previously segreg ated materials may be thoroughly re- mixed and used when representative samples taken anywhere in the stockpile indicated a uniform gradation exists. (3) Cement and Supplemental Cementitious. Protect cement and supplemental cementitious materials in storage or stockpiled on the site from any damage by climatic conditions which would change the characteristics or usability of the material. (4) Moisture. Provide aggregate with a moisture cont ent of ± 0.5% from the averag e of that day. If the moisture content in the aggregate varies by more than the above tolerance, take whatever corrective measures are necessary to bring the moisture to a constant and uniform consistency before placing concrete. This may be accomplished by handling or mani pulating the stockpiles to reduce the moisture content, or by adding moisture to the stockpiles in a manner producing uniform moisture content through all portions of the stockpile. For plants equipped with an approved accurate mois ture-determining device capab le of determining the free moisture in the aggregates, and provisions made for batch to batch correction of the amount of water and the weight of aggregates added, the requirements relative to manipulating the stockpiles for moisture control will be waived. Any procedure used will not relieve the producer of the responsibility for delivering concrete of uniform slump within the limits specified.
5.Separation of Materials in Te sted and Approved Stockpiles. Only use KDOT Approved Materials. Provide separate means for storing ma terials approved by KDOT. If the producer elects to use KDOT Approved Materials for non-KDOT work, during the progress of a project requiring KDOT Approved Materials, inform the Engineer and agree to pay all costs for additional material testing. Clean all conveyors, bins and hoppers of any unapproved materials before beginning the manufacture of concrete for KDOT work. 401 - GENERAL CONCRETE 400-7 401.5 MORTAR AND GROUT
a.General. Follow the proportioning requirements in subsection 401.5b. and c. for mortar and grout unless otherwise specified in the Contract Documents, including altering the proportions when a minimum strength is specified.
b.Mortar. Mortar is defined as a mixture of cementitious materials, FA-M aggregate and water, which may contain admixtures, and is typically used to minimize erosion between large stones or to bond masonry units. Proportion mortar for laying stone for stone rip-rap, slope protection, stone ditch lining or pavement patching at 1 part of portland cement and 3 parts of FA-M aggregate by volume with sufficient water to make a workable and plastic mix. Proportion mortar for laying brick, concrete blocks or stone masonry at ½ part masonry cement, ½ part portland cement and 3 parts FA-M aggregate, either commercially produced masonry sand or FA-M, by volume with sufficient water to make a workable and plastic mix. Do not use air-entraining agents in mortar for masonry work. The Engineer may visually accept the sand used for mortar. The Engineer may visually accept any recognized brand of portland cement or masonry cement that is free of lumps.
c.Grout. Grout is defined as a mixture of cementitious materials with or without aggregate or admixtures to which sufficient water is added to produce a pouring or pump ing consistency without segr egation of the constituent materials and meeting the applicable specifications. 401.6 COMMERCIAL GRADE CONCRETE If the Contract Documents allow the use of commerci al grade concrete for designated items, then use a commercial grade mixture from a ready mix plant approved by the Engineer. The Engineer must approve the commercial grade c oncrete mixture. Approval of the commercial grade mixture is based on these conditions: All materials are those normally used for the productio n and sale of concrete in the vicinity of the project. The mixture produced is that normally used for the pr oduction and sale of concrete in the vicinity of the project. The mixture produced contains a minimum cementitious content of 6 sacks (564 lbs) of cementitious material per cubic yard of concrete. The water-cementitious ratio is as designated by the Engineer. The maximum water-cementitious ratio permitted may not exceed 0.50 pounds of water per pound of cementitious material including free water in the aggregate. Type I, II, III, IP, IS or IT cement may be used unless otherwise designated. Fly ash, slag cement and blended supplemental materials may be substituted for the required minimum cement content as specified in subsection 401.3 . No additives other than air entraining agent will be allowed. The Contractor will not be required to furnish the results of strength tests when submitting mix design data to the Engineer. In lieu of the above, approved mix designs (including optimized) for all other grades of concrete, Grade 3.0 or above, are allowable for use as commercial grade conc rete, at no additional cost to KDOT. Exercise good engineering judgment in determining what equipment is used in proportioning, mixing, transporting, placing, consolidating and finishing the concrete. Construct the items with the best curr ent industry practices and techniques. Before unloading at the site, prov ide a delivery ticket for each load of concrete containing the following information: Name and location of the plant. Time of batching concrete. Mix proportions of concrete (or a mix designation approved by the Engineer). Number of cubic yards of concrete batched. 401 - GENERAL CONCRETE 400-8 Cure the various items placed, as shown in DIVISION 700 . The Engineer may test commercial grade concrete by molding sets of 3 cylinders. This is for informational purposes only. No slump or unit weight tests are required. 401.7 CERTIFIED CONCRETE If KDOT inspection forces are not available on a tempor ary basis, the Engineer may authorize the use of concrete from approved concrete plants. Approval for this operation is based on certification of the plant and plant personnel, according to KDOT standards. KDOT’s ap proval may be withdrawn an y time that certification procedures are not followed. Contact the DME for additional information. The Engineer will not authorize the use of certified co ncrete for major structures such as bridges, RCB box bridges, RCB culverts, permanent main line and ramp pavement or other structurally, critical items. Each load of certified concrete must be accompanied by a ticket listing mix proportions, time of batching and setting on revolution counter, total mixing revolutio ns and must be signed by certified plant personnel. 401.8 MIXING, DELIVERY AND PLACEMENT LIMITATIONS
a.Concrete Batching, Mixing and Delivery. Batch and mix the concrete in a central mix plant, in a truck mixer or in a drum mixer at the work site. Provide plant capacity and delivery capacity sufficient to maintain continuous delivery at the rate required. The delivery rate of concrete during concreti ng operations must provide for the proper handling, placing and finishing of the concrete. Seek the Engineer’s approval of the concrete plant/batch site before any concrete is produced for the project. The Engineer will inspect the equipment, the method of storing and handling of materials, the production procedures and the transportation and rate of delivery of concrete from the plant to the point of use. The Engineer will grant approval of the concrete plant/batch site based on compliance with the specified requirements. The Engineer may, at any time, rescind permission to use concrete from a previ ously approved concrete plan t/batch site upon failure to comply with the specified requirements. Clean the mixing drum before it is charged with the conc rete mixture. Charge the batch into the mixing drum such that a portion of the water is in the drum before the aggregates and cementitious material. Uniformly flow materials into the drum throughout the batching operation. All mixing water must be in the drum by the end of the first 15 seconds of the mixing cycle. Keep the throat of the drum free of accumulations restricting the flow of materials into the drum. Do not exceed the rated capacity (cubic yards shown on the manufacturer’s plate on the mixer) of the mixer when batching the concrete. The Engineer may allow an ove rload of up to 10% above the rated capacity for central mix plants and drum mixers at the work site, provided the concrete test data for strength, segregation and uniform consistency are satisfactory, and no concre te is spilled during the mixing cycle. Operate the mixing drum at the sp eed specified by the mixer’s manufact urer (shown on the manufacturer’s plate on the mixer). Mixing time is measured from the time all materials, ex cept water, are in the drum. If it is necessary to increase the mixing time to obtain the specified percent of air in air-entrained concrete, the Engineer will determine the mixing time. If the concrete is mixed in a central mix plant or a drum mixer at the work site, mix the batch between 1 to 5 minutes at mixing speed. Do not exceed the maximum to tal 60 mixing revolutions. Mi xing time begins after all materials, except water, are in the drum, and ends when the discharge chute opens. Transfer time in multiple drum mixers is included in mixing time. Mix time may be reduced for plants utilizing high performance mixing drums provided thoroughly mixed and uniform concrete is being pr oduced with the proposed mix time. Performance of the plant must conform to Table A1.1 of ASTM C 94, Standard Specification for Ready Mixed Concrete. Five of the 6 tests listed in Table A1.1 must be within the limits of the specification to indicate that uniform concrete is being produced. If the concrete is mixed in a truck mixer, mix the batch between 70 and 100 revolutions of the drum or blades at mixing speed. After the mixing is completed, set the truck mixer drum at agitating speed. Unless the mixing unit is equipped with an accurate device indicati ng and controlling the number of revolutions at mixing speed, perform the mixing at the batch plant and operate the mixing unit at agitating speed while travelling from the plant to the work site. Do not exceed 300 total revolutions (mixing and agitating). An additional 60 mixing revolutions may be allowed by the Engineer when plasticizers are designated in the mix design. 401 - GENERAL CONCRETE 400-9 If a truck mixer or truck agitator is used to transport concrete that was completely mixed in a stationary central mixer, agitate the concrete while transporting at the agitating speed specified by the manufacturer of the equipment (shown on the manufacturer’s plate on the equi pment). Do not exceed 200 total revolutions (additional re-mixing and agitating). Provide a batch slip including batch weights of ever y constituent of the concrete and time for each batch of concrete delivered at the work site, issued at the batchi ng plant that bears the time of charging of the mixer drum with cementitious materials and aggregates. Include quantities, type, product name and manufacturer of all admixtures on the batch ticket. On paving projects and other high volume work, the Engineer will evaluate the haul time, and whether tickets will be collected for every load. Thereafter, random checks of the loads will be made. Maintain all batch tickets when not collected. When non-agitating equipment is us ed for transportation of concrete, pl ace within 30 minutes of adding the cement to the water. Provide approved covers for protection against the weather when required by the Engineer. When agitating equipment is used for transportation of the concrete, place concrete within the time and temperature conditions shown in TABLE 401-5 . TABLE 401-5: AMBIENT AIR TEMPERATURE AND AGITATED CONCRETE PLACEMENT TIME T = Ambient Air Temperature at Time of Batching (°F) Time limit agitated concrete must be placed within, after the addition of cement to water (hours) Admixtures T < 75 1 ½ None 75 ≤ T 1 None 75 ≤ T < 90 1 ½ Set Retarder In all cases, if the concrete temperature at time of placement is 90°F or above, or under conditions contributing to quick stiffeni ng of the concrete, place the concrete within 45 minutes of adding the cement to the water. Do not use concrete that has developed its initial set. Regardless of the speed of delivery and placement, the Engineer will suspend the concreting operations until correc tive measures are taken, if there is evidence that the concrete cannot be adequately consolidated. Weather conditions and the use of admixtures can affect the set times for the concrete. Do not use the time limits and total revolutions as the sole criterion for rejection of concrete. Exceed the time limits a nd total revolutions only after demonstrating that the properties of the concre te can be improved. Evaluation of the consistency and workability should be taken into cons ideration. Reject concrete that cannot be adequately consolidated. Adding water to concrete after the initial mixing is prohibited, with this exception: If the concrete is delivered to the work site in a truck mi xer, the Engineer will allow water (up to 2 gallons per cubic yard) be withheld from the mixture at the batch site, and if needed, added at the work site to adjust the slump to the specified requirements. Determine the ne ed for additional water as soon as the load arrives at the construction site. Use a calibrated water-measuring device to add the water, and add the water to the entire load. Do not add more water than was withheld at the batch site. After the additio nal water is added, turn the drum or blades an additional 20 to 30 revolutions at mixing speed. The Engineer will supervise the adding of wate r to the load, and will allow this procedure only once per load. Conduct all testing for acceptance and produce any required cylinders after all water or admixtures have been added. Do not add water at the work site if the slump is with in the designated slump tolerance, even if water was withheld. Do not add water at the work site if the percent air is above 8%, regardless of the slump, even if water was withheld. Do not withhold and add water if plasticizer is a dded to the concrete mixture at the batch site. If at any time during the placement of concrete it is determined that redosing with water is adversely affecting the properties of the concrete, the concrete will be rejected and the Engineer will suspend the practice.
b.Placement Limitations.
1.Placing Concrete at Night. Do not mix, place or finish concrete without su fficient natural light, unless an adequate, artificial lighting system approved by the Engineer is provided. 401 - GENERAL CONCRETE 400-10
2.Placing Concrete in Cold Weather. Unless authorized by the Engineer, discontinue mixing and concreting operations when the descen ding ambient air temperature reaches 40°F. Do not begin concreting operations until an ascending ambient air temperatur e reaches 35°F and is expected to exceed 40ºF. If the Engineer permits placing concrete during cold w eather, aggregates may be h eated by either steam or dry heat system before placing them in the mixer. Use an apparatus that heat s the mass uniformly and is so arranged as to preclude the possible occurrence of overheated areas which might injure the materials. Do not heat aggregates directly by gas or oil flame or on sheet metal over fire. Aggregates that are heated in bins, by steam-coil or water- coil heating, or by other methods not detrimental to the aggregates may be used. The use of live steam on or through binned aggregates is prohibited. Unless otherw ise authorized, maintain the temperature of the mixed concrete between 50 to 90°F at the time of placing. Do not, under any circumstances, continue concrete operations if the ambient air temperature is less than 20°F. If the ambient air temperature is 35°F or less at the time the concrete is placed, the Engineer may require that the water and the aggregates be heated to between 70 and 150°F. Do not place concrete on frozen subgrade or use frozen aggregates in the concrete. Make adjustments for potential longer set time and slower strength gain for concrete with SCMs. Adjust minimum time requirements as stated in SECTION 710 for concrete used in structures. For concrete paving, be aware of the effect that th e use of SCMs (except silica fume) may have on the statistics and moving averages. 401.9 INSPECTION AND TESTING Unless otherwise designated in the Contract Documents or by the Engineer, obtain samples of fresh concrete for the determination of slump, weight per cubic ya rd and percent of air from the final point of placement. The Engineer will cast, store and test strength test specimens in sets of 3. KDOT will conduct the sampling and test the samples according to DIVISION 2500 and the Sampling and Testing Frequency Chart in Part V. For QC/QA contracts, establish testing intervals within the specified minimum frequency. The Engineer will reject concrete that does not comply with specified requirements. The Engineer will permit occasional deviations below th e specified cementitious content, if it is due to the air content of the concrete exceeding the designated air c ontent, but only up to the maximum tolerance in the air content. Continuous operation below the specified cementitious content for any reason is prohibited. As the work progresses, the Engineer reserves the righ t to require the Contractor to change the proportions if conditions warrant such changes to produce a satisfactory mix. Any such changes may be made within the limits of the specifications at no additional compensation to the Contractor. 401 - GENERAL CONCRETE 400-11 APPENDIX A – NON-MANDATORY INFORMATION GENERAL CONCRETE Design general concrete according to TABLE 401-A1 meeting the applicable requirements for Volume of Permeable Voids, Surface Resis tivity, or Rapid Chloride Permeability as required in subsection 401.3h . TABLE 401-A1: GENERAL CONCRETE Grade of Concrete lb. of Cementitious per yd of Concrete, minimum lb. of Water per lb. of Cementitious, maximum Grade 7.0(**): MA Gradation 700 0.35 Grade 6.0(**): MA Gradation 650 0.35 Grade 5.0(**): MA Gradation 602 0.35 Grade 4.5(**): MA Gradation 602 0.40 Grade 4.0(**): MA Gradation 602 0.44 Grade 3.5 and 3.0(**): MA Gradation 564 0.46 Grade 2.5(**): MA Gradation 526 0.50 General Concrete (*) (**) *Grade as specified in the Contract Documents **Air Entrained meeting subsection 401.3a . Air entrained concrete with a target air of 6.5 ± 1.5 percent. Maximum water to cementitious ratio of 0.50 and a minimum cementitious content of 480 lbs per cubic yard. Maximum limit of lb. of water per lb. of cementitious material includes free water in aggregates, but excludes water of absorption of the aggregates. 401 - GENERAL CONCRETE 400-12 APPENDIX B – NON-MANDATORY INFORMATION SUGGESTED GUIDELINES FOR MEETING KDOT ’S PERMEABILITY SPECIFICATIONS General: Water and chlorides permeate through the mortar and paste of the concrete mixes. They do not readily permeate through the larger aggregates. Permeability can be improved by decreasing the mortar and paste of the concrete mix and increasing the coarse aggregate portions. The use of optimized mix designs, blended cements, and/or supplementary cementitious materials (SCMs) can reduce the permeability of concrete. SECTIONS 1102 and 1116 , Aggregates for Concrete describes optimized aggregate gradations for concrete mixes. Additional tes ting for alkali silica reaction (ASR) is required when SCMs are used in concrete as per SECTION 401 . The amount of SCMs required to pass the ASR testing may be different than the amount required to comply with the permeability specifications. SCMs may also lower the necessary water cement (w/c) ratio and may slow set times and strength gain. Optimizing the coarse aggregate gradations can decrease permeability. This includes mixes with more than 60% retained on the # 8 sieve and gradations with fineness modulus above 4.75. A fineness modulus of over 5.0 can yield even better results. Use the largest practi cal nominal maximum size aggregate allowed. In general, keeping the w/c ratio below 0.43 may help meet the permeability specifications, as may lower cementitious content mixes when using Type I/II cements. These two properties control the paste in the mix. Concrete mixes with less than 25% paste (as displayed on KDOT Form 694) are more likely to pass the permeability specifications. Acceptable concrete can be mixed with past e contents of 23% or lower. Water cement ratios below 0.39 often do not provide enough wate r for all constituents to properly react, especially when admixtures are used, and may be counterproductive. High early strength conc rete mixes using Type III cement and higher cementitious contents have also been able to pass the Standard Pe rmeability requirements because of their low w/c ratios. In general, the use of water reducers is helpful in reducing the paste content. Material compatibilities, following the admixture suppliers’ recommendations for dosage rates, and the order of introduction of the chemicals into the mix are paramount to meeting KDOT specifications. Contractors should work with their admixture suppliers to find an admixture that works well with their combination of materials. Changes made to an approved mix design will change the permeability, especially additional water, or redosing water that was withheld from the mix at a concrete plant. It is also recommended that concrete producers verify their mixes with a minimum of 3 cubic yards after doing their laboratory mix designs. Standard Permeability Co ncrete (SPC) Requirements: Volume of Permeable Voids 12.0% max, or Surface Resistivity 9.0 k Ω-cm min, or RCPT 3000 Coulombs max. The SPC requirements may be met without the use of optimized mix designs, blended cements or SCMs. With certain aggregates, 25% slag cement will be requir ed to pass the ASR testing. With other aggregates, a minimum of 30% slag cement by weight of total cementitious materials is usually needed. Some fly ashes require a minimum of 18% to 20% of the total cementitious materi al to pass the ASR test. Class C fly ash will react differently than Class F fly ash. Some people believe that lower absorption aggregates have a better chance of meeting the permeability specification, but higher absorption aggregates have been used in concrete mixes utilizing these guidelines and have met the SPC specifications. KDOT has found that the properties of the concrete are often more important than the absorption of the aggr egate when meeting this specification. Moderate Permeability Co ncrete (MPC) Requirements: Volume of Permeable Voids 11.0% max, or Surface Resistivity 13.0 k Ω-cm min, or RCPT 2000 Coulombs max. Concrete mixes for MPC will require aggregates with a minimum Soundness of 0.95, a maximum LA Wear of 40, and a minimum Acid Insoluble Residue of 85%. These aggregates, by nature, are harder aggregates with very low absorption. MPC may rely more heavily on optimized gradations, blended cements or SCMs in order to meet the specification. Consideration could be given to ternary blends of cementitious materials, using more than one 401 - GENERAL CONCRETE 400-13 SCM, or combining a blended cement with an additional SCM. Combinations of 25% to 30% slag cement with as little as 10% to 25% Class C fly ash have been very effective in keeping permeabilities below the level required for MPC. Incorporation of 20% Class F Fly Ash will often satisfy the requirements of the MPC specification. Low Permeability Concrete (LPC) Requirements: Volume of Permeable Voids 9.5% max, or Surface Resistivity 27.0 k Ω-cm min, or RCPT 1000 Coulombs max. LPC will also use harder aggregates with very low absorption. These mixes must be optimized with the MA-6 gradation. Mix designs with 5% silica fume and 95% Type I/II cement often meet the LPC requirements. These mixes have traditionally been known as silica fume concrete. Ternary mix designs are useful in meeting these requirements. Consider using 3% to 5% silica fume with 25% to 30% slag cement, or 25 % to 30% slag cements with 10% to 25% Class C fly ash. Class F fly ash alone may also be effective in reducing the permeability to these levels. Contact KDOT’s Bureau of Research or the Distri ct Office for additional guidance in meeting the Permeability Specifications. 402 – STRUCTURAL CONCRETE
400-14 Section 402
STRUCTURAL CONCRETE 402.1 DESCRIPTION Provide the grades of concrete sp ecified in the Contract Documents. This specification is specific to Structural Concrete. See SECTION 401 for general concrete requirements. 402.2 MATERIALS Provide materials that comply w ith the applicable requirements. General Conc rete .................................................................................................... … SECTION 401 Aggregate ............................................................................................................... ….. DIVISION 1100 Admixtures, and Pl asticizers ................................................................................. ….. DIVISION 1400 Cement, Fly Ash, Silica Fume, Slag Cement and Blended Supplemental Cementitious ........................................................................................................... …. DIVISION 2000 Water ………………………………………………………………. ..................... ….. DIVISION 2400 402.3 CONCRETE MIX DESIGN
a.General. Design structural concrete mixes as specified in the Contract Documents.
b.Concrete Mix Design. Two options are available for mix desi gn procedures. Use the procedures outlined in SECTION 401 or Appendix A to design structural concrete mixes. Mixes developed using Appendix A must meet permeability requirements of TABLE 402-1 .
c.Concrete Strength Requirements. Design concrete to meet the strength requirements of SECTION 401.
d.Portland Cement, Blended Hydraulic Cemen t, and Individual and Blended Supplemental Cementitious Materials. Unless specified otherwise in the Contract Documents, sel ect the type of portland cement, blended hydraulic cement and indi vidual and blended supplemental cementitious materials according to SECTION 401.
e.Structural Concrete Specific Requirements. Design concrete to meet the following requirements:
1.Maximum water to cementitious ratio of 0.50 and a minimum cementitious content of 480 lbs per cubic yard.
2.Air entrain concrete with a target air content of 6.5 ± 1.5 percent.
3.Determine the air loss due to pumping operations once in the AM and once in the PM. Determine the difference between the air content from concrete sampled before the pump, and concrete sampled after pumping. Make adjustment to the mix to compensate for the pumping of the concrete.
4.Maximum air content is 10%. Ta ke immediate steps to reduce the ai r content whenever the air content exceeds 8%.
5.Determine air content by KT-19 (Volumetric Me thod). A regularly calibrated KT-18 (Pressure Method) meter may be used for production with random verification by the Volumetric Method. See KT-19 for special requirements when using the Volumetric Method with high cemen titious concretes or mixtures with midrange water reducers or plasticizers.
6.Concrete permeability requirements according to TABLE 402-1 .
7.Use Quality Requirements for Structural Aggregates as listed in SECTION 1102 , Aggregates For Concrete Not Placed on Grade.
8.Use gradation requirements for aggregates as listed in SECTION 1102 , Aggregates For Concrete Not Placed on Grade.
9.Use MA-6 optimized gradation for Low Permeability Concrete for Bridge Overlays. 402 – STRUCTURAL CONCRETE
400-15 (10) Perform 28-day Volume of Permeable Voids as per KT-73, 28-day Surface Resistivity as per KT-79,
or 56-day Rapid Chloride Permeability as per AASHTO T-277 when required . Submit accelerated cure procedures for the Engineer’s approval. The field verification test procedure must be the same test procedure as the mix design approval test.
11.To meet permeability requirements, the use of supplemental cementitious materials may be necessary. See SECTION 401 .
12.When used, add silica fume with other cementitious materials during batching procedures. If the silica fume cannot be added to the cementitious materials, add th e loose silica fume to the bo ttom of the stationary drum that is wet, but has no standing water, before adding the dry materials. The Engineer may approve shreddable bags on a performance basis, only when a central batch mixing process is used. If so, add the bags to half of the mixing water and mix before adding cementitious materials, aggregate and remainder of water. Mix silica fume modified concrete for a minimum of 100 mixing revolutions.
13.ASTM C-1567 is required if supplementar y cementitious materials (SCMs) are utilized. See subsection 401.3d.(6) for requirements. ASTM C 1567 is not necessary for concrete modified with only Silica Fume.
f.Slump.
1.Designate a slump for each conc rete mix design that is required for satisfactory placement of the concrete application. Reject concrete with a slump th at limits the workability or placement of the concrete.
2.If the designated slump is 3 inches or less, the tolerance is ±3/4 inch, or limited by the maximum allowable slump for the individual type of construction.
3.If the designated slump is greater than 3 inches the tolerance is ±25% of the designated slump.
4.For drilled shafts the target slump just prior to being pumped into the drilled shaft is 9 inches. If the slump is less than 8 inches, redose the concrete with admixtures as permitted in subsection 401.3i .
5.Do not designate a slump in excess of 5 inches for all other structural concrete. TABLE 402-1: REQUIREMENTS FOR STRUCTURAL CONCRETE Volume of Permeable Voids, maximumSurface Resistivity, minimum Rapid Chloride Permeability, maximum ASTM C-1567 Accelerated Mortar Bar Expansion Use Low Permeability Concrete (LPC) for Bridge Overlays 9.5% 27.0 kΩ-cm 1000 Coulombs 0.10% @ 16 days Use Moderate Permeability Concrete (MPC) for specified Full Depth Bridge Decks. 11.0% 13.0 kΩ-cm 2000 Coulombs 0.10% @ 16 days Use Standard Permeability Concrete (SPC) for all other structural concrete not specified as Low or Moderate Permeability. 12.0% 9.0 k Ω-cm 3000 Coulombs 0.10% @ 16 days 402 – STRUCTURAL CONCRETE
400-16 Appendix A – Non-Mandatory Information
GENERAL CONCRETE FOR STRUCTURES AND SILICA FUME MODIFIED CONCRETE CONCRETE FOR STRUCTURES Design concrete for st ructures according to TABLE 402-A1 meeting the applicab le requirements for Volume of Permeable Voids, Surface Resistivity or Rapid Chloride Permeability as required in TABLE 402-1 . TABLE 402-A1: CONCRETE FOR STRUCTURES Grade of Concrete lb. of Cementitious per yd of Concrete, minimum lb. of Water per lb. of Cementitious, maximum Grade 6.0(**)(***)(****): MA Gradation 700 0.35 Grade 5.0(**)(***)(****): MA Gradation 602 0.35 Grade 4.5(**)(***)(****): MA Gradation 602 0.40 Grade 4.0(**)(***)(****): MA Gradation 602 0.44 Grade 3.5 and 3.0(**): MA Gradation 564 0.46 Grade 2.5(**): MA Gradation 526 0.50 Structural Concrete (*) (**) (***)(****) *Grade as specified in the Contract Documents **Air Entrained meeting subsection 402.3e. ***Aggregate as specified in DIVISION 1100 . ****MPC (Moderate Permeability Concrete) Air entrained concrete with a target air of 6.5 ± 1.5 percent. Maximum water to cementitious ratio of 0.50 and a minimum cementitious content of 480 lbs per cubic yard. Maximum limit of lb. of water per lb. of cementitious material includes free water in aggregates, but excludes water of absorption of the aggregates. SILICA FUME MODIFIED CONCRETE When silica fume is selected for use in structur al concrete, meet the mix design and production requirements in TABLE 402-A2 . Use MA-6 Aggregate Gradation for Bridge Overlay concrete. TABLE 402-A2: SILICA FUME BRIDGE OVERLAY CONCRETE CRITERIA lbs. of Cement per cu. yd. maximum 595 lbs. of Silica Fume per cu. yd., maximum 30 lbs. of water per lbs. of (Cement + Silica Fume), maximum 0.40 Percent of Air by Volume 6.5±1.5 Maximum 28 day Permeable Voids KT-73 9.50% or Minimum 28 day Surface Resistivity KT-79 27.0 kΩ-cm or Maximum 56 day Rapid Chloride Permeability T-277 1000 coulombs 403 – ON GRADE CONCRETE
400-17 Section 403
ON GRADE CONCRETE 403.1 DESCRIPTION Provide the grades of concrete sp ecified in the Contract Documents. This specification is specific to On Grade Concrete. See SECTION 401 for general concrete requirements. 403.2 MATERIALS Provide materials that comply w ith the applicable requirements. General Conc rete. ........................................................................................................ SECTION 401 Aggregate ............................................................................................................... ….. DIVISION 1100 Admixtures and Pl asticizers .................................................................................. ….. DIVISION 1400 Grade 2 Calcium Chloride ...................................................................................... ….. DIVISION 1700 Cement, Fly Ash, Silica Fume, Slag Cement and Blended Supplemental Cementitious ........................................................................................................... …. DIVISION 2000 Water ………………………………………………………………. ..................... ….. DIVISION 2400 403.3 CONCRETE MIX DESIGN
a.General. Design the concrete mixes for on grade concre te as specified in th e Contract Documents.
b.Concrete Mix Design. Use procedures outlined in SECTION 401 .
c.Portland Cement and Blended Hydraulic Ceme nt and Supplemental Cementitious Materials. Unless specified otherwise in the Contract Document s, select the type of portland cement, blended hydraulic cement and supplemental cemen titious materials as specified in SECTION 401 .
d.On Grade Concrete Specific Requirements. Use Optimized, Air-Entrained Concrete. Provide the Engineer written notification of the selection prior to the pre-construction conference.
1.Design air-entrained concrete for pavement meeting TABLE 403-1 .
2.Design air-entrained concrete for shoulders meeting TABLE 403-2 .
3.Design air-entrained concrete for other uses with a maximum water to cementitious ratio of 0.50 and a minimum cementitious content of 480 lbs per cubic yard.
4.For projects that are not QC/QA paving projects, verify the mix design in the field by performing compressive strength tests on cylinders made from samples taken from concrete produced at the project site before or during the first day that concrete pavement is placed on the project. If the comp ressive strength tests indicate noncompliance with minimum design values, add additional cement to the mix or make other appropriate mix design changes at no additional cost to KDOT.
5.Control air content for PCCP by subsection 403.4 .
6.The amount of cementitious material listed in TABLES 403-1 and 403-2 is the designated minimum for concrete pavement and shoulders respectively. It may be necessary to add additional cementitious material or otherwise adjust the mix proportions as permitted by the specifications to provide a mix design that complies with the compressive strength requirement.
7.Maximum limit of lb. of water per lb. of cementiti ous material includes free water in aggregates, but excludes water of absorp tion of the aggregates.
8.Provide On Grade Concrete that meets either th e 28-day Volume of Permeable Voids KT-73, 28-day Surface Resistivity KT-79, or 56-day Rapid Chloride Permeability AASHTO T-277. Submit accelerated cure procedures for the Engineer’s approval. The field verification test procedure must be the same test procedure as the mix design approval test.
9.Permeability requirements do not apply for concrete patching material used in SECTION 833 when existing pavement to be patched is more than 10 years old. 403 – ON GRADE CONCRETE 400-18 TABLE 403-1: AIR-ENTRAINED CONCRETE FOR PAVEMENT lb. of Cementitious per yd3 of Concrete, minimum lb. of Water per lb. of Cementitious, maximum Percent of Air by Volume 28-Day Comp Strength, psi minimum Volume of Permeable Voids, maximum Surface Resistivity, minimum Rapid Chloride Permeability, maximum 517 0.45 See subsection 403.3e. 4000 12.0% 9.0 kΩ-cm 3000 Coulombs TABLE 403-2: AIR-ENTRAINE D CONCRETE FOR SHOULDERS lb. of Cementitious per yd3 of Concrete, minimum lb. of Water per lb. of Cementitious, maximum Percent of Air by Volume Volume of Permeable Voids, maximum Surface Resistivity, minimum Rapid Chloride Permeability, maximum 480 0.45 See subsection 403.3e. 12.0% 9.0 kΩ-cm 3000 Coulombs
10.Concrete for shoulders using the same aggregates, gradations, and water to cementitious ratio as the mainline pavement concrete on the same project will be approved without testing for Volume of Permeable Voids, Surface Resistivity or Ra pid Chloride Permeability.
e.Design Air Content. Provide a minimum air content that complies with these 2 criteria: a minimum by volume of 5.0% behind the paver, and a maximum air void spacing factor of 0.0100 inch behind the paver. For a typical PCCP, design the mix at the minimum air content plus 0.5%. The target air content is the air cont ent that meets both criteria above. If the air void spacing factor exceeds 0.0100 inch, use the following formula as a guide to determine the target air content: Minimum % air content at 0.0100 inch = % air meas ured + (measured spacing factor – 0.0100)/0.0010. Mixes with Laboratory or Field Prequalification spaci ng factors greater than 0.0100 inch will not be approved. When AVA spacing factors exceed 0.010 inches (0.25 mm) take imme diate steps to reduce the spacing factor. The Field Engineer will conduct an investigation using the following steps. If any one of the steps 1 through 9 corrects the problem, the Field Engineer will stop the investigation. The steps may be completed in combination and/or out of order. For example some may want to conduct steps 5 or 6 before some of the other steps.
1.If the failing sample came from behind the paver, the Engineer will take the following steps. Obtain an AVA sample from a unit weight bucket of concrete obtained from grade in front of the paver. Also, measure the total air content in the concrete on the grade in front of the paver. Obtain AVA and total air samples from behind the paver. Determine the loss of air and spacing factor due to the paving op eration. Adjust for air loss due to paving.
2.Verify calibration of the AVA. 3. Change the location of the AVA during testing.
4.Call in the Research Unit or another AVA machine for comparison testing.
5.Check the mix design for compliance with SECTION 401 . 403 – ON GRADE CONCRETE
400-19 6. Check all of the gradations.
7.Check the total air content vs. target air content.
8.Check for Contractor compliance with admixture supplier’s recommendations on dosage rates and order of introduction of the chemicals into the mix.
9.Check for material compatibility by using di fferent admixtures or sources of admixtures. Refer to the “11 Strategies to Impr ove the Air-Void Spacing Factor” in APPENDIX B . If the problem is not corrected, the Field Engineer will take the following steps: Obtain 2 cores from any area with an AVA spacing factor >0.0125 inches and send to Materials Research Center for hardened air evaluation. If the AVA spacing factor > 0.0125 inches and the average hardened air spacing factor is > 0.0080 inches, then suspend paving and submit new mix design. If the AVA spacing factor > 0.0125 inches and the average hardened air spacing factor < 0.0080 inches, then accept PCCP. Take immediate steps to increase the air content wh enever the air content behind the paver falls below 5.0%. Suspend paving operations when 2 consecutive air c ontents behind the paver fall below 4.0% and remove and replace the represented concrete. Air Void Spacing Factor does not apply to concrete used in SECTION 833 when existing pavement to be patched is more than 10 years old. The maximum air content is 10%. Take immediate steps to reduce the air content whenever the air content exceeds 8%.
f.Slump.
1.Maximum design slump for slip form On Grade Concrete is 2 ½ inches. Do not designate a slump in excess of 5 inches for all other On Grade Concrete
2.For all other On Grade Concrete placement, designate a slump that is required for satisfactory placement of the concrete application. Reject concrete w ith a slump that limits the wo rkability or placement of the concrete.
3.If the designated slump is 3 inches or less, the tolerance is ±3/4 inch, or limited by the maximum allowable slump for the individual type of construction.
4.If the designated slump is greater than 3 inches the tolerance is ±25% of the designated slump. 403.4 AIR-ENTRAINED ON GRADE CONCRETE
a.Air Content for PCCP. Provide an air content that complies with subsection 401.3e . Using fresh concrete, the Engineer will determine th e air void spacing factor using the AVA according to the manufacturer’s requirements. Prequalify mixtures by e ither the laboratory option or the field option. Contact the Engineer to arrange testing by the AVA. Additional AVA testing will be required if the concrete plant is changed during the course of the project.
b.Laboratory Prequalification. Prepare a trial mix using a drum -type mixer according to AASHTO T 126 using all of the materials in the proportions, except the air entraining agent, contemplated for use in the field. Laboratory mixes require more air entraining agent than is needed in the field. The Engineer will perform the following: Consolidate a sample in the unit weight bucket by vibration according to KT-20. Obtain 3 samples fro m the unit weight bucket for testing by the AVA. Valid results must have a minimum of 2 spacing factor readings within a range of 0. 0025 inch. Test the third sample if the first 2 do not meet these criteria. Determine the ai r content of the trial mix by KT-19 (Volumetric Method) or KT-18 (Pressure Method) calibrated to yield the same result. Calculate a target percent air content at a maximum air void spacing factor of 0.01 inch using the equation in subsection 403.3e. , when applicable.
c.Field Prequalification. Produce a trial batch at a minimum air temperature of 60ºF using the batch plant and project materials. The Engineer will perform the following: Test for air content by the procedure specified under laboratory prequalification. Correlate this air c ontent to the average of at least 2 valid AVA test results. Valid AVA results have a maximum range of 0.0025 inch. 403 – ON GRADE CONCRETE
400-20 When necessary, calculate a target percent air content at a maximum air void spacing factor of 0.0100 inch,
using the equation in subsection 403.3e .
d.Field Verification. Coordinate with the Engineer so production samples may be obtained behind the paver to establish the target air content on the first paving day. Produce concrete using the same materials and proportions that were used in the prequalification mixture. Adjustments may be approved in the dosage of air entraining agent and a 5% adjustment may be approved in the water-cementitious ratio. AVA samples will be taken both in the path of a vibrator and the gap between vibrators. Perform the test for air content at the delivery site of the concrete KT-19 (Roll-a-meter) or KT-18 (pressure meter), calibrated to yield the same result. Make adjustme nts in the proportions, types of material or the operation to establish a satisfactory, target air content.
e.Control of the Air Conten t During Paving Operations. Maintain an air content behind the paver as determined by KT-19 or KT-18, which meets subsection 403.3e . Maintain all production parameters established during field verification. The dosage of air-entraining agent may be varied to control the air content. Five percent adjustments will be permitted to the cementitious content and the water-cementitious ratio. With AVA testing, 5% adjustments will be permitted to the aggregate proportions, as well as any adjustment to the water reducer. Comply with all specifications regarding production of fresh concrete. For all mainline paving, test the concrete at the beginning of the day’s operation and approximately every 2 hours thereafter for air content. For all other slipformed pavement, test for air content at the beginning of a day’s operation and approximately every 4 hours thereafter. Test hand placements for air content at least once daily. Determine the air loss due to paving operations once in the AM and once in the PM. Determine the difference between the air content from concrete sampled be fore the paver, and concrete sampled behind the paver. QC/QA samples may be obtained in front of the paver and then corrected subtracting the difference determined during that ½ days production. Loss of air due to paving operations may adversely affect the spacing factor. Failure to maintain the minimum required air content will result in suspension of operation. Take immediate steps to increase the air conten t above the minimum values stated in subsection 403.3e . Other similar designs using higher cementitious contents (this may adversely affect permeability) and the same admixture types and dosage (with the same or lowe r water-cementitious ratio) may be used in limited areas such as crossovers, etc. Unauthorized changes in any aspect of production are cause for rejection of the pavement. Random checks of the air void spacing factor of the concrete in the path and gap of the vibrators will be conducted by the Engineer to verify a maximum spacing factor of 0.0100 inch at the measured air content. 403 – ON GRADE CONCRETE
400-21 Appendix A – Non-Mandatory Information
GENERAL ON GRADE CONCRETE Design On Grade Concrete according to TABLE 403-A1 meeting the applicable requirements for Volume of Permeable Voids, Surface Resistivity or Rapid Chloride Permeability as required in TABLE 403-1 . TABLE 403-A1: ON GRADE CONCRETE Grade of Concrete lb. of Cementitious per yd of Concrete, minimum lb. of Water per lb. of Cementitious, maximum Grade 4.0: MA Gradation 602 0.44 Grade 3.5 and 3.0: MA Gradation 564 0.46 Grade 2.5: MA Gradation 526 0.50 Air Entrained On Grade Concrete meeting subsection 403.3e . Maximum water to cementitious ratio of 0.50 and a minimum cementitious material content of 480 lbs per cubic yard. Maximum limit of lb. of water per lb. of cementitious material includes free water in aggregates, but excludes water of absorp tion of the aggregates. APPENDIX B – NON-MANDATORY INFORMATION STRATEGIES TO IMPROVE THE AIR VOID SPACING FACTOR Better air-void characteristics are obtained by a more thorough mixing of the sand and the air-entraining agent. Below are listed some strategies to help the mixing process.
1.Increase the mixing time of the plant or mixing revolutions of the truck.
2.Use a higher dosage of water reducer, up to 390 ml per 100 kg (6 oz. per 100 lbs) of cement. Use a non-retarding water reducer above 195 ml per 100 kg (3 oz. per 100 lbs) if needed.
3.Reduce the Paste Content (less water or less cement).
4.Use a higher proportion of rock.
5.Use a third, mid-sized aggregate.
6.Use coarser graded sand, or a finer sand if the current one is extremely coarse.
7.Maintain a higher air content (use more air-entraining agent).
8.Use coarser cement.
9.Change types or brands of the water reducer or the air entraining agent or both.
10.Cool the mix ingredients; i.e., use chilled water.
11.Use a different plant or modify the plant configuratio n. Introduce aggregates together on the belt feed (multiple weigh hoppers), use live bottoms aggregate bins, use dual drums, etc. 404 – CONCRETE FOR PRESTR ESSED CONCRETE MEMBERS
400-22 Section 404
CONCRETE FOR PRESTRESSED CONCRETE MEMBERS 404.1 DESCRIPTION Provide concrete with the release and 28 day compre ssive strengths specified in the Contract Documents. This specification is specific to Concrete for Prestressed Concrete Members. See SECTION 401 for general concrete requirements. 404.2 MATERIALS Provide materials that comply w ith the applicable requirements. General Conc rete .................................................................................................... … SECTION 401 Aggregate ............................................................................................................... ….. DIVISION 1100 Admixtures and Pl asticizers .................................................................................. ….. DIVISION 1400 Grade 2 Calcium Chloride ...................................................................................... ….. DIVISION 1700 Cement, Fly Ash, Silica Fume, Slag Cement and Blended Supplemental Cementitious ........................................................................................................... …. DIVISION 2000 Water ………………………………………………………………. ..................... ….. DIVISION 2400 404.3 CONCRETE MIX DESIGN
a.General. Design concrete mixes specified in the Contract Documents. A mix design must be approved by the Engineer before the mix can be used in the production of prestressed concrete members.
b.Concrete Mix Design. Two options are available for mix desi gn procedures. Use the procedures outlined in SECTION 401 , or use TABLE 404-2 to design structural concrete mixes.
c.Concrete Strength Requirements. Unless shown otherwise in the Contract Documents, design concrete to meet the compressive strength requirements of TABLE 404-1 . For prestressed bridge beams, the Engineer will determine the strength requirements from the table except when specified elsewhere in the Contract Documents. TABLE 404-1: COMPRESSIVE STRENGTH REQUIREMENTS Type of Unit For Stress Application (Release) and/or moving* (Minimum) (psi) Age 28 Days (Minimum)** (psi) Prestressed Bridge Beams 5800 7000 4800 6000 4000 5000 Prestressed Piles 3000 5000 Prestressed Panels 4000 5000 * From casting bed to producer’s storage only. Not a shipping strength. ** Also required for shipping strength.
d.Portland Cement, Blended Hydraulic C ement and Individual and Blended Supplemental Cementitious Materials. Unless specified otherwise in the Contract Documents, sel ect the type of portland cement, blended hydraulic cement and indi vidual and blended supplemental cementitious materials according to SECTION 401. 404 – CONCRETE FOR PRESTR ESSED CONCRETE MEMBERS
400-23 e. Specific Requirements for Concrete used in Prestressed Concrete Members. Design concrete to
meet the requirements of TABLE 404-2 . TABLE 404-2: CONCRETE REQUIREMENTS Self-Consolidatin g Concrete (SCC) Non SCC All Concrete Slump Flow From Target (Inches) Blocking Assessment (Inches) Visual Stability Index Maximum Slump (Inches) Minimum Cementitious per Cubic Yard (Lbs) Mixing Water: Maximum lb. per lb. Cementitious Air Content (%) ± 2 2 maximum 0 or 1 5 or 7 ± 25% 602 0.44 6.5 ± 1.5
1.Determine the slump flow using ASTM C 1611, “Standard Test Method for Slump Flow of Self- Consolidating Concrete.” The target value is determined during the mix design and approval process (see below). At the point of placement, slump flow can deviat e from target by no more than 2 inches.
2.Determine the blocking assessment using ASTM C 1621, “Standard Test Method for Passing Ability of Self-Consolidating Concrete by J-Ring.”
3.Determine the visual stability index (VSI) using Appendix X1 of ASTM C 1611. When approved by the Engineer, the VSI may be determined using additional concrete stability observations.
4.Designate a slump for each concre te mix design that is no greater than 5 inches when not using mid- range or high-range water reducing admixtures. When a water reducing admixture is being used, designate a slump no greater than 7 inches. The tolerance from design at the point of delivery is ± 25%.
5.It may be necessary to adjust the mix proportions, as permitted by the specifications, to provide a mix that complies with placement, and the rel ease and 28-day strength requirements.
6.Maximum limit of lb. of water per lb. of cementitious material includes free water in aggregates, but excludes water of absorp tion of the aggregates.
7.Non-air entrained concrete may be used in co ncrete piling not subject to freezing and thawing and wetting and drying.
8.There are no permeability requirements.
9.Determine air content by KT-19 (Volumetric Me thod). A regularly calibrated KT-18 (Pressure Method) meter may be used for production with random verification by the Volumetric Method. See KT-19 for special requirements when using the Volumetric Method with high cemen titious concretes or mixtures with midrange water reducers or plasticizers.
10.Use Quality Requirements for St ructural Aggregates as listed in SECTION 1102 , Aggregates For Concrete Not Placed on Grade. Keep a copy of the KDOT O fficial Quality test report from the approved source on file at the prestress plant and ava ilable for review by the Engineer.
11.Use gradation requirements for aggregates as listed in SECTION 1102 , Aggregates For Concrete Not Placed on Grade.
12.When used, add silica fume with other cementitious materials during batching procedures. If the silica fume cannot be added to the cementitious materials, add th e loose silica fume to the bo ttom of the stationary drum that is wet, but has no standing water, before adding the dry materials. The Engineer may approve shreddable bags on a performance basis, only when a central batch mixing process is used. If so, add the bags to half of the mixing water and mix before adding cementitious materials, aggregate and remainder of water. The presence of visible chunks or wads of bag paper at the point of placement will be caus e for rejection. Mix silica fume modified concrete for a minimum of 100 mixing revolutions, unless high speed mixing equipment is used.
13.ASTM C-1567 is required if supplementar y cementitious materials (SCMs) are utilized. See subsection 401.3d.(6) for requirements. ASTM C 1567 is not necessary for concrete modified with only Silica Fume.
14.For the approved source of water, keep a copy of the KDOT test report on file at the prestress plant and available for review by the Engineer.
15.Use admixtures that are prequalified. Maintain a copy of the Type C certification on file at the prestress plant and available for review by the Engineer. No other additives may be used without written approval by the Engineer. 404 – CONCRETE FOR PRESTR ESSED CONCRETE MEMBERS
400-24 f. Additional Design Requirements fo r Self-Consolidating Concrete (SCC). SCC is defined as a concrete
mixture which can be placed by means of its own weight with little to no vibra tion. It is accomplished by adjusting traditional mix designs using special admixtures.
1.Do not rod or vibrate when making test cylinders. (2) Provide scales capable of determining test block weights for the strand bond test that are calibrated (NIST traceable) and approved by the Engineer.
3.Perform a strand bond test (KT-83) for each mix a nd strand to be used in the future production of prestressed beams. Any change in admixture, aggregate s ource or gradation, cementitious material content or source, and strand producer or size requires that a new strand bond test be completed using the replacement materials. Make 2 test beams for each bond test. Cure the te st beams in an environment that is re presentative of future production (i.e. – moisture and heat until release then ambient conditions).
a.With the Engineer observing, perform a single Sl ump Flow test for each pair of test beams cast. This spread establishes a target value from whic h future point of placement values are to be compared to. Assign a Visual Stability I ndex (VSI) number to the concrete spread.
b.With the Engineer observing, perform a single J-Ring test for each pair of test beams cast. Calculate a “blocking assessment” value.
c.Make a minimum of 2 sets of 3 cylinders for each pair of test beams cast. Cure the cylinders with the test beams they represent.
i.With the Engineer observing, test 1 set of cylinders at the producer’s plant to measure for release (equal to the release strength of future production). De-tension the strand in both test beams only after this cylinder set indicates that release strength has been attained. (ii) With the Engineer observing, test 1 set of cylinders at the producer’s plant to measure for 28-day strength (equal to the 28-day strength of future production). Perform the bond test on both test beams only after this cylinder set indicates that the 28-day strength has been attained. (iii) In both cases, the required strength is met when the average compressive strength of the 3 cylinders equals or exceeds the re quired strength, and no more than 1 cylinder in the tested set had a strength that was no more than 5% below the required strength.
d.With the Engineer observing, measure the dimensions of both test beams to verify the required casting tolerances. Calculate the we ight of the required test loads.
e.With the Engineer observing, load the test beams using the calculated loads and KT-83. (f) Submit all beam dimensions, cal culations (intermediat e and final), release and 28-day strengths, observations, measurements, pictures, and test results related to strand bond, cylinder strength, slump flow, and J-ring testing to the Engineer for review.
g.In addition to the requirements of this section and SECTION 401 , the mix design represented by this testing may be approved provided there are 2 passing bond tests, and the assigned blocking assessment and the calculated VSI satisfy the requirements of TABLE 404-2 . 405 – CURING ENVIRONMENT
400-25 Section 405
CURING ENVIRONMENT 405.1 DESCRIPTION Provide a curing environment for storage of KDOT concrete cylinders made during open span bridge concrete placements. The curing envi ronment would be utilized by KDOT to store the cylinders during the first 48 hours of their initial cure (KT-22). The curing environmen t needs to be of sufficient size to hold test samples required for the project at any given time. The quantity of test samples will be based on the appropriate sampling and testing frequency chart in Part V. The curing environment does not apply to test specimens made for PCCP, curb and gutter, sidewalk, etc. BID ITEM UNITS C u r i n g E n v i r o n m e n t L u m p S u m 405.2 MATERIALS Provide a curing environment that meets the Initial Curing requirements of KT-22. Provide a thermometer that records the high and lo w temperatures within the curing environment. 405.3 CONSTRUCTION REQUIREMENTS During the preconstructio n meeting, discuss with the Engineer th e necessary capacity and location of the curing environment. Locate the curing environment to allow the Engineer access at all times. When KDOT cylinders are stored in the curing environment, provide the Engineer with the recorded high and low temperatures within the curing environment, daily. 4005.4 MEASUREMENT AND PAYMENT The Engineer will measure curing environment by the lump sum. Payment for "Curing Environment" at the contract unit price is full compensation for the specified work. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-1 Section 501
PORTLAND CEMENT CONCR ETE PAVEMENT (QC/QA) Note: PCCP is considered QC/QA when the bid item Qualit y Control Testing is included in the contract. Note the exceptions in subsection 501.5. 501.1 DESCRIPTION Construct Portland Cement Concrete Pavement (PCCP) on a prepared subgrade or base course. Develop and perform quality control testing. Urban PCCP Environment: Projects or sections of the project classified as Urban Type are typically: within city limits; require pieced construction due to: business and residential entrances; frequency of side streets; or project phasing. Before paving, meet with the Engineer to determine if th e project or sections of th e project are classified as Urban Type. B I D I T E M S U N I T S Concrete Pavement (* Uniform) (AE) (**) Square Yard Concrete Pavement (* Variable) (AE) (**) Square Yard Early Strength Concrete Pavement (* Uniform) (AE) (**) Square Yard Early Strength Concrete Pavement (* Variable) (AE) (**) Square Yard Quality Control Testing (PCCP)+ S q u a r e Y a r d Concrete Core (Set Price) Each * Thickness ** No entry denotes PCCP with mesh and dowel assemblies. "Plain" denotes PCCP without mesh and dowel assemblies. "NRDJ" denotes non-reinforced dowel jointed PCCP. "Br App" denotes bridge approach pavement. + Br App pavement quantities are not included in this item. 501.2 CONTRACTOR QUALITY CONTROL REQUIREMENTS
a.General . Provide qualified personnel and sufficient equi pment complying with the requirements listed in Part V to conduct quality control testing that complie s with Appendix B, Sampling and Testing Frequency Chart for Concrete Construction Items for Qua lity Control/Quality Assurance Projects. Allow the Engineer access to the C ontractor’s laboratory to observe te sting procedures, calculations, test documentation and plotting of test results. Calibrate and correlate the testing equipment with prescribed procedures, and conduct tests in compliance with specified testing procedures as listed in Part V. Maintain a Quality Manual in the field laboratory showing the calibrations performed on all test equipment and when the next calibration is due for that equipment. As a minimum, follow the calibration/verification interval established in Table 1: Concrete Materials Test Equipment in Section 5.2.7.4-Concrete: Contractor’s Quality Control Plan, Part V. See also Section 5.2.7.5-Exampl e of a Laboratory Quality Manual for Concrete, Part V.
b.Quality Control Plan (QCP). At the pre-construction conference, submit to the Engineer for approval by the DME, a QCP as outlined in Section 5.2.7.4-Concre te: Contractor’s Quality Control Plan, Part V. Follow 5.2.7.4: Concrete: Contractor’s Quality Control Plan in Part V as a general guideline. Keep a printed copy of the approved QCP in the Contractor’s laboratory and make available to the Engineer when requested. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-2 The Contractor’s laboratory and equipment will be inspected and approved as outlined in Section 5.2.7-
Contractor’s Quality Control Plan, Part V. Include a listing of the names and phone numbers of individuals and alternates responsible for quality control administration and inspection. On the Contractor’s organizational chart, show the specified lines of authority relating both to mi x design and quality control ope rations during production. Po st the organizational chart in the Contractor’s test facility. Provide a quality control organization or private testing firm having pe rsonnel certified according to the Policy and Procedures Manual for The Certified Inspection and Testing (CIT) Training Program. The testing for this type of construction will require personnel certified in A ggregate Field Tester (AGF), Aggregate Lab Technician (AGL), Profilograph (PO), ACI Concrete Field Testing T echnician (CF), Nuclear Mois ture Density Gauge Tester (NUC) and Hardened Concrete Properties (HCP) classifications. Provide a minimum of 1 employee on the project certified in the QC/QA Concrete/Cement Treated Base Specs (QCS) classification. Only persons certified in the appropriate classificati ons covering the specific tests required shall perform such testing. At the beginning of the project, provide the Engineer with the list of certified technicians and alternates, phone numbers and tests/insp ection they will be performing. As personnel changes and certifications may expire, continue to provide the Engineer with an accurate list. Provide an organizational chart showing the specified lines of authority relating to both mix design and quality control operations duri ng production. Identify the company offici al acting as liaison with KDOT, and the Certified Technician who will direct inspection and testing. Post the chart in the test facility.
c.Required Duties of Certified Technicians. Be available on the project s ite whenever concrete for pavement is being produced a nd being placed on the project site. Perform and utilize quality control tests and other quality control practices to assure th at delivered materials and proportioni ng meet the requirements of the mix designs. Periodically inspect all equipment u tilized in transporting, proportioning, mixing, placing, consolidating, finishing and curing to assure it is operating properly and that placement, consolidation, fi nishing and curing comply with the mix design and other contract requirements.
d.Contractor’s Testing Facilities. Describe the testing facility and its accreditation in the QCP. Locate the testing facility either at the plant site or at the project. Obtain approval of the testing facilities and location from the DME before the commencement of mixture production. Provide suitable space for the required testing equipment. Also, equip th e testing facility with these items for the exclusive use of the testing facility ’s quality control personnel and the Engineer: A telephone with a private line; A copying machine; and Broadband internet connection (for 1 computer). If the Engineer determines that broadband internet service is not available, provide a fax machine, at no additional cost.
e.Documentation. Include in the QCP procedures, charts and forms to be used to provide the required documentation. Record and document all test results and calculations. Record all original documentation in a bound field book or other KDOT approved bound record and turn over to KDOT at the end of the project. At all times, have complete records of all inspections and tests readily available on site for the Engineer. All records documenting the Contracto r’s quality control inspections and te sts become the property of KDOT upon completion of the work. Indicate the nature and number of observations made , the number and type of deficiencies found, the quantities approved and rejected, and the corrective action taken in the records. Examples of quality control forms and charts are available in Part V, or Contractors may design their own. Documentation procedures are subject to approval by the Engineer before the start of the work and to compliance checks during the progress of the work. Maintain control charts on an ongoing basis. Plot data according to SECTION 106 . Record specific test results on a Daily Quality Control Summary sheet designed to facilitate the computation of moving test averages. Base moving averages on 4 consecutive test results. Include a description of quality control actions taken (such as adjustment of aggregate or additiv e proportions in the mix, moisture adjustments) in the Daily Quality Control Summary Sheet. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-3 Provide forms on a computer-acceptable medium, where required. Document ticke ts and gradation data
according to KDOT requirements. Complete testing and charting within 1 working day after sampling. Keep all quality control charts current. Show both individual test results and moving average values. As a minimum on approved control charts, plot the single test values and the 4 test moving average values for these properties: Percent air in concrete mixture; Slump of concrete mixture; Concrete unit weight; In-place concrete density on plas tic concrete as a percentage of determined unit weight; and Combined aggregate gradation (as a minimum, plot the 3/8" and No. 8 sieves). Also plot the single test values for actual workability and target workability of the combined aggregates. Provide the following test data to the KDOT Project Representative: Copies of all test results and control charts on a weekly basis, representing the prior week’s production; Copies of the quality control summary sheet on a daily basis. Include, as a minimum, combined aggregate gradations, actual workability and target workability of combined aggregates, percent air content, slump, concrete un it weight and density of fre sh concrete in-place; and Copies of all failing test results. Include all applicable sieves, actual workability, percent air content, slump and density of fre sh concrete in-place. Copies of vibrator checks daily to the Inspector. Email a weekly r ecap to the Construction Engineer. Email or fax the data to the Field Engineer and DME, weekly.
f.Testing Requirements. In the QCP, identify test methods, procedures and equipment proposed for use. Use standard KDOT test methods and pr operly calibrated measuring and testing equipment as outlined in Part V. Detail any alternative sampling method, procedure or inspec tion equipment proposed to be used. Such alternatives are subject to review and approval by the DME. Take all samples for tests and perform in-place te sts at random locations, se lected according to the Contractor’s QC Plan and at the rates specified in the Sampling and Testing Frequency Chart for Portland Cement Concrete Pavement for Quality Control/Quality Assurance Projects in Appendix B, Part V. Retain the latest 10 gradation samples for use by the Engineer.
g.Corrective Action. In the QCP, identify procedures for notifying the Engineer when corrective measures must be implemented, and for halting production. Notify the Engineer when the movi ng average test result trend line for any property approaches the specification limits. Cease operations if 2 consecutive moving average points fall outside the specification limits. Ceasing operations is the Contractor’s responsibility. Quality control tests for this determination include aggregate gradation, compliance with the mix design band, percent ai r content, concrete unit we ight and density of fresh concrete in-place. Failure to cease operations for the conditions cited above will subject all subsequent material to rejection, or acceptance at a reduced price, as determined by the Engineer. The Engineer may examine materials represented by individual test results, which lie beyond the Contractor’s normal quality control testing variation. The investigation may be based on either Contractor or KDOT test results. The information from additional testing (includi ng testing of in-place pavement) may be used to define unacceptable work according to SECTION 105 . The Engineer will apply appropriate price reductions or initiate corrective action. If a dispute exists between the Engineer and Contractor about the validity of any test results other than compressive strengths or thickness de termination, the KDOT District Mate rials Laboratory or MRC will perform referee testing. If one of the disputed KDOT test results was generated at th e MRC, then an independent laboratory agreeable to both parties will be selected. The AASHTO Accreditation Program shall have approved the selected laboratory for the appropriate test procedure. If referee testing indicates that KDOT te st results are correct, the 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-4 Contractor is responsible for the cost of additional testi ng, including referee testing pe rformed at the MRC. If the
referee testing indicates that the Contr actor test results are correct, KDOT is responsible for the cost of additional testing. Follow the procedures outlined in subsection 501.5g.(4) if a dispute arises for any test determining compressive strengths or thickness.
h.Non-Conforming Materials . In the QCP, specifically addre ss how non-conforming materials will be controlled and identified. Establish and maintain an effective and positive sy stem for controlling non-conf orming material, including procedures for its identification, is olation and disposition. Reclaim or rework non-conf orming materials according to procedures acceptable to the Engineer. Identify all non-conforming materials and products to prevent use, shipment and intermingling with conforming materials and products. Pr ovide holding areas, mutually agreeable to the Engineer and Contractor.
i.Concrete Information. Separately list the grades of concrete involved in the project. For each grade of concrete to be used, include at a minimum, the following: Mix designs. List mix design numbers if using existing mixes. Aggregate production. Quality of components. Stockpile management. Proportioning, including added water. Mixing and transportation. Initial mix properties. Placement and consolidation. Concrete yield. Compressive strength. Finishing and curing. Frequency of sampling and testing. How duties and responsibilities are to be accomplis hed and documented, and if more than one Certified Technician is required. The criteria used by the Certified Technician to correct or reject unsatisfactory materials. 501.3 MATERIALS Provide materials that comply with the applicable requirements. Concrete and Grout ................................................................................. SECTIONS 401& 403 Aggregates for On Grade Concrete ......................................................... SECTION 1116 Reinforcing Steel ..................................................................................... DIVISION 1600 Epoxy Coated Steel Bars for Concrete Reinforcement ........................... DIVISION 1600 Joint Sealants ........................................................................................... DIVISION 1500 Expansion Join t Fille r ............................................................................. DIVISION 1500 Concrete Curing Material s ...................................................................... DIVISION 1400 Preformed Elastomeric Co mpression Joint Seals .................................... DIVISION 1500 Cold Applied Chemically Cured Joint Sealant ........................................ DIVISION 1500 Hot Type Joint Sealing Compound ......................................................... DIVISION 1500 Backer Rod .............................................................................................. DIVISION 1500 Epoxy Resin-Base Bonding Sy stem for Concrete ................................... SECTION 1705 Bond Breakers ......................................................................................... SECTION 1718 501.4 CONSTRUCTION REQUIREMENTS
a.Preparation of the Subgrade. Before placing any surfacing materi al on any section, complete the ditches and drains along that section to effectively drain the highway. Trim the base or subgrade to the line, grade 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-5 and typical cross-section as shown in the Contract Documents. Maintain the subgrade or base to the as-constructed
condition under other bid items, repairing any encountered def ects to the specifications of those bid items. Maintain the subgrade surface to readily drain at all times. Protect the subgrade from da mage when handling materials, tools and equipment. Do not store or st ockpile materials on the subgrade. Do not place material or lay pavement on a frozen or muddy subgrade, or when it is raining or snowing. Lightly spray the subgrade or base with water to obtain a thoroughly mois tened condition when the concrete is deposited on it. Do not puddle water on the grade. Do not deposit any material until the subgrade or base has been checked and approved by the Engineer.
b.Slip Form Paving. When paving is performed with a slip fo rm paving unit, use equipment as described in subsection 154.5 . Pave 24-foot wide mainline paveme nt in a single operation. Do not exceed 24-foot paving width in a single operation except as follows: The Contractor may pave a maximum of 2 lanes plus a 6-foot shoulder (30 feet maximum) in a single operation. For pavements of 3 lanes or more, pave a minimum of 2 lanes mainline (with the option of including a single shoulder for a maximum of 30 feet) in a single operation. Approval will be based on satisfactory performance of the Contractor’s operation. Place ramps and auxiliary lanes/shoulders as shown in the Contract Documents. Once the paving operation has started, provide adequate equipment and supply of materials to maintain continuous placement for any given working period. Keep all conc rete conveying equipment clean. Do not apply any tractive forces to the slip form paver, except that which is controlled from the machine. Trim to grade the subgrade or surf ace of the base over which the tracks of the paver will travel. Do not disturb this surface with other equipmen t. If the equipment or method of opera tion requires the subbase to be wider than shown in the Contract Documents, place additional material to provide an adequate surface for the tracks of the paver. Upon completion of the paving ope rations, remove or repair any base material damaged by the slip form paver’s tracks. All necessary constructi on and removal of this additional base ma terial is subsidiary to other items of the contract. Operate the paver continuously, stoppi ng only when absolutely necessary . If the forward motion of the paver is stopped, immediately stop the vibrator and tamping elements. Deposit the concrete on the grade in successive batche s to minimize re-handling. Place concrete over and against any joint assemblies so the joint assembly is retained in its correct position. Spread the concrete using approved mechanical spreaders to prevent segregation and separation of the materials. After striking the concrete off with the spreader, leave sufficient conc rete in place to allow the final shaping by the use of screeds, templates and pans, de pending on make, model and type of machines approved for use in the paving train. Adjust the paving units to meet the required final cross-section, minimizing the need to carry back concrete to fill voids or depressions. Adjust each screed or te mplate so a uniform roll of concrete extends the full length of the screed or template and a llows just enough concrete to pass under the unit to properly feed the next machine. Do not shove large volumes of conc rete with the screed or template. Adjust the screed or template to maintain a uniform cross-section. Use multiple spreaders for single and multiple lift opera tions. Place concrete ahead of the initial spreader strikeoff no more than 30 minutes ahead of the final spreader strikeoff. The use of any paving machine in the paving train is contingent on its ability to finish the pavement satisfactorily to the required grade, s ection and specified degree of consolida tion. The Engineer may at any time require the adjustment, repair or replacement of the machine for unsatisfactory performance. Correct any edge slump of the pavement in excess of ¼ inch, exclusive of edge rounding, before the concrete hardens. Excessive edge slumping will be sufficient reason to discontinue paving until machinery (or mix) is properly adjusted or removed from the project. When the machine finishing has been completed, check the surface with a straightedge a minimum of 10 feet in length before texturing. Operate the straightedge parallel to the pavement centerline, starting at the center and progressing outward. Advance in successive stages of less than ½ the length of the straightedge. At the Contractor’s option, this requirement may be eliminated when smoothness is to be determined by the profilograph. Achieve grade control by use of 1 or more of the following grade reference devices. Approval of any of these devices will be based upon satisfactory performance. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-6 Erected Stringline. Use an erected stringline consisting of a tightly stretched wire or string offset from and
parallel to the pavement edge on 1 or both sides. Erect the stringline paralle l to the established pavement surface grade and support at intervals as necessary to maintain the established grade and alignment. Stringless Paving. Control line, grade and pavement cross-section as shown in the Contract Documents. Use electronic guidance systems that meet the requirements and tolerances listed in SECTION 802 . Horizontal control is guided by GPS. Vertical control is guided by Total Stations. GPS will not be allowed for Vertical control. When paving on a fresh subgrade that has not been trimmed by an automatically controlled machine, use an erected stringline or stringless paving to establish gr ade. When directed by th e Engineer, use an erected stringline or stringless paving to match grade control points such as bridges.
c.Placing Reinforcement. Place pavement reinforcement at th e locations shown in the Contract Documents. Use a sufficient number of approved metal, bar supports or pins to hold all dowel bars and tie bars in proper position as required by th e Contract Documents. Install tie-bars pe rpendicular to the concrete face being tied together. Do not use stones, concrete or wood to support the reinforcement. Joint tie bars may be installed mechanically if appr oved by the Engineer. The satisfactory placement of the bars depends on the ability of the Contr actor’s operation to place and maintain th e bars in their true position. When satisfactory placement is not obtained by mechanical means, the Engineer may re quire the tie bars be installed ahead of placing the concrete, and that they be securely held in their exact position by staking and tying. Do not install dowel bars mechanically. Install th e dowel bars ahead of placing the concrete, and hold them securely in their exact position by staking or tying. Thoroughly coat each dowel with hard grease or othe r approved bond breaker as shown in the Contract Documents. The bond breaker coating shall not exceed 15 m ils ± 5 mils in thickness when averaged over 3 points measured at the ¼ points on the bar at 90º intervals around the bar. When reinforced concrete pavement is placed in 2 laye rs, strike off the entire wi dth of the bottom layer to such length and depth that the sheet of fabric or bar mat may be laid full length on the concrete in its final position without further manipula tion. Place the reinforcement di rectly on the concrete, then pl ace the top layer of concrete, strike it off and screed it. Remove any portion of the bo ttom layer of concrete that has been placed more than 30 minutes, and replace it with fresh mixed c oncrete at the Contractor’s expense. When reinforced concrete is placed in 1 layer, the reinforcement may be positioned in advan ce of the concrete placement or it may be placed in the plastic concrete after initial spreading, by mechanical or vibratory means. Place the wire mesh reinforcement in the pavement at the locations s hown in the Contract Documents. When 2 layers of wire mesh reinforcement are required, support the bottom layer in the required position with bar chairs. Use separators for the top layer if the strike -off can not be used properly for the operation. Lap the reinforcement as shown in the Contract Documents. Laps parallel to the centerline of the pavement are prohibited except for unusual width of pavement lanes or for irregular areas. If the Contract Documents do not show dimensions for laps, the minimum lap either perpendicular or parallel to the centerline of the pavement is 6 inches. Fasten or tie adjacent wire mesh sheets together to hold all parts of the wire mesh sheets in the same plane. If a “wire pattern” appears on the su rface of the fresh pavement, immedi ately modify placement procedures to eliminate the problem. Use reinforcing steel free from detrimental materials that could impair the bond between the steel and concrete.
d.Consolidation and Finishing. Perform hand spreading with shovels, not rakes. Do not allow workers to walk in the fresh concrete with boots or shoes coated with earth or foreign substance. Do not apply moisture to the surface of the concrete pavement unless the Engineer approves the use of additional water on the fresh concrete su rface to lubricate the float of the l ongitudinal finisher. If unusual weather conditions require the addition of superficial water to the concrete surface, apply it only in the form of a fine, fog mist. Uniformly consolidate the concrete without voids, and finish to the cross-section and elevation shown in the Contract Documents. Use vibrators or other appr oved equipment to consolidate each layer of concrete, when placed in more than 1 lift, or full depth if placed in 1 lift. Uniformly vibrate the concrete across the full width and depth of the pavement so that the density of pavement concrete is a minimum of 98% of the consolidated unit weight. The 98% density 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-7 requirement may be eliminated on miscellaneous areas such as entrance pavement, median pavement and gore
areas. Vibrators, either of the surface type (pan or screed) or the immersion ty pe (tube or spud) may be attached to the spreader, paver or finishing machine, or may be mounted on a separate carriage. Only operate the vibrators when the machine they are mounted on is moving forward. Do not operate hand vibrators more than 15 seconds, or less than 5 seconds in any one location unless approved otherwise by the Engineer. Place vibrators in and withdraw from concrete vertically in a slow deliberate manner. On mainline paving, every 4 hours, check the electronic monitoring system vibrator frequencies with the vibrator under load to comply with the frequencies shown in subsection 154.2e . If the system indicates a vibrator is not working properly, manually check the vibrators, immediately. If a vibrator is not f unctioning properly, i mmediately replace. If the electronic monitoring system fails to operate properly, manually check the vibrators, immediately. If the vibrators are functioning properly, paving may continue but make all efforts to correct the problem within 3 paving days. The Engineer may allow additional time if circumstances are beyond the Contractor’s control. Perform the vibrator checks manually until the system is fixed. Document the checks, and give the da ta to the Inspector, daily. Email a recap of the data to the Engineer, weekly. Maintain a uniform, continuous roll of concrete over the vibrators ahead of the strike-off. The height of the roll shall be approximately the same height as the thickness of the pavement being vibrated. In order to obtain concrete consolidation in the vicin ity of joint assemblies, the Engineer may require that these areas be hand vibrated with an immersion spud vibrator. In the event the specified density is not attained, cease paving opera tions and make necessary adjustments to produce concrete to conform to the density requirements. Use an approved nuclear density meas uring device to monitor in-place dens ity. Provide a moveable bridge and move it to test locations as required to allow the Inspector to work over the fresh concrete. On projects or areas within projects where the use of conventional equipment is impracticable, other consolidation and finishing equipment may be used with approval of the Engineer.
e.Fixed Form Paving. At the Contractor’s option, the fixed form paving method may be used.
1.Forms. Use straight, metal forms having adequate strength to support the equipment. Each section shall be a minimum of 10 feet in length. Use forms with a depth equal to the prescribed edge thickness of the concrete, a base width at least equal to the depth of the fo rms and without a horizontal joint. Use flexible or curved forms of proper radius for curves of 150-foot radius or le ss, except approved straight forms of 5-foot lengths may be used for curves of a radius from 75 to 150 feet. Flexible or curved forms must be approved by the Engineer. The Engineer may approve the use of wood forms in areas re quiring hand finishi ng. Secure the forms in place to withstand the impact and vibration of the consolidating and finishing equipment without visible spring or settlement. Extend flange braces out ward on the base a minimum of ⅔ the height of the form. Remove forms with battered top surfaces or bent, twisted or broken forms. Do not use repaired forms until they have been inspected and approved by the Engineer. Do not use buildup forms, except where the total area of pavement of any specified thickness on the project is less the 2,000 square yards. Do not vary the top face of the form from a true plane more than ⅛ inch in 10 feet, and do not vary the vertical face of th e form by more than ¼ inch. The forms shall contain provisions for locking the ends of abutting form s ections together tightly, and for secure setting.
2.Base Support. Provide a foundation under the forms that is compact and true to the specified grade so that the whole length of the form will be set firmly in contact with the grade.
3.Form Setting. Set forms sufficiently in advance of the point where concrete is being placed so that line and grade may be checked. After the forms have been corr ectly set, thoroughly tamp the grade mechanically at both the inside and outside edges of the base of the forms. Stake forms into pl ace with a minimum of 3 pins for each 10 feet section. Place a pin at each side of every joint. Tightly lo ck form sections, free from play or movement in any direction. Do not deviate the form from true line by more than ¼ inch at any point. No excessive settlement or springing of forms under the fi nishing machine is permitted. Clean and oil forms before the placing of concrete.
4.Grade and Alignment. Check the alignment and grade elevations of the forms immediately before placing the concrete and make any necessary corrections. When any form has been disturbed or any grade has become unstable, reset and recheck the form.
5.Placing Reinforcement and Consolidating and Finishing Concrete. Meet the requirements in subsections 501.4c. and d. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-8 (6) Removing Forms. Unless otherw ise provided, do not remove forms from freshly placed concrete until
it has set for a minimum of 12 hours, except auxiliary form s used temporarily in widened areas. Remove forms carefully to avoid damage to the pavement.
f.Texturing. Use texturing equipment and devices as described in subsection 154.7 . Use a burlap drag as soon as all excess moisture has disappeared and while the concrete is still plastic enough to make a granular surface possible. Following the dragging operation, use a mechanical device to make a final finish or texture by giving the surface of the plastic pavement a longit udinal tining, unless shown otherwise in the Contract Documents. Perform the operation at such time to minimize displacement of larg er aggregate particles and be fore the surface permanently sets. Small or irregular areas may be tined by hand methods. On projects of less than 5,000 square yards, or projects with longitudinal tining, the tining and curing devices may be mounted on the same ca rriage when approved by the Engineer. Operations of this type will be based on satisfactory performance. Before final texturing, finish the exposed edge of the pa vement to a radius of ¼ inch with an edger. Edge the interior longitudinal joints on multiple-lane pavement to a radius of ⅛ inch. Eliminate any tool marks appearing on the slab adjacent to the jo ints or edge of the slab. Do not dist urb the rounding of the corner of the slab.
g.Joints.
1.General. Construct joints accordi ng to the Contract Documents. Failu re to construct the joints in the best possible manner will be cause for suspension of work until the cause of the defective work is remedied. If existing pavement of any type is required to abut with the new pavement, and the termination of the removal is not at an existing joint, make the new joint by sawing the existing pavement full depth with a diamond saw before removal. The objective is to create or form a plane of weakness in the fresh conc rete before uncontrolled or erratic cracking occurs. The following methods are acceptable: Use concrete saws to saw all contraction joints no wider than the initial saw cut and to a depth of D/3 ± ¼ inch. Extreme conditions could exist which make it impracticable to prevent erratic cracking by sawing the joints early. At the onset of the project, devise methods, with the approval of the Engineer, to control this cracking. Make a “plastic concrete cut” straight and well de fined so it can be sawed out by the saw crew. The “plastic concrete cut” would replace the specified in itial saw cut. Suggested procedures could be the use of a stiff metal parting strip, with or without handles that would be gently inserted in the fresh concrete and removed, thereby parting the interl ocking coarse aggregate and providing a plane of weakness. Cut the fresh concrete with a mason’s trowel and stra ightedge from a worker’s bridge. It is imperative that the “plastic concrete cut” joint and the second stage saw cut are in the same exact location. At the Contractor’s option, “early entry” saws may be used based on satisfactory performance and depth of cut recommended by the equipment manufacturer. Procedures to control erratic cracking are not limited to these examples. Edge any transverse joint requiring hand finish ing and edging with a tool having a radius of ⅛ inch. Do not indent the surface of the pavement with the horizontal face of the edger.
2.Pressure Relief Joints. Install pressure relief jo ints according to the bridge approach details in the Contract Documents. Form or saw openings for the joint material approximately 1 ¾ inches wide for the 2-inch joint and approximately 3 ¾ inches wide for the 4-inch joint at the locations shown in the Contract Documents. Use the lubricant adhesive as recommended by the manufacturer of the pressure relief joint material. Just before the installation of the jo int material, clean the faces of the joint by sandblasting, followed by an air blast to clean all dust from joint faces. The Engineer may approve pre-positioning of the 2-inch material if adequate means are taken to obtain proper placement and retention, and if de formation of the material does not occu r when the fresh concrete is placed against it. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-9 Use a foam spacer block beneath the 4- inch joint filler material to maintain the specifi ed grade. The spacer
block is an easily compressed foam material cut to fill the void beneath the joint filler.
3.Contraction Joints. Install contraction joints of the type, dimensions and spacing shown in the Contract Documents. Stretch a stringline along the centerline of the joint, or otherwise adequately mark it to verify dowel bar joint assembly alignment. Install the dowel bar joint assembly so the centerline of the assembly is perpendicular to the centerline of the slab, and the dowels lie parallel to the slab surface and slab cen terline. Place concrete so it will not displace or disarrange the joint assembly. Mark the location of contraction joints to assure the joints are sawed in the proper location.
4.Longitudinal Joints. Construct longitudinal joints according to the Contract Documents. When sawed joints are specified or used, provide approved guide lines or devices to cut the longitudinal joint on the true line as shown in the Contract Documents. Perform the sawing of longitudinal joints at a time that will prevent erratic or uncontrolled cracking. When “plastic concrete cut” met hods are used, no sawing or widening of the joint will be required to make a sealant reservoir.
5.Construction Joints. Make a butt construction joint perpendicular to the center line of the pavement at the close of each day’s work, or when the process of depositing concrete is stopped for a length of time sufficient for the concrete to take its initial set. Form this joint by using a clean header having a nominal thickness of 2 inches, and minimum cross-sectional area equal to pavement thickness by pavement width. Cut the header true to the crown of the finished pavement. A ccurately set and hold it in place in a pl ane at right angles to centerline and perpendicular to the surface of the pavement. Protect the top surface of the header with steel. Securely fasten a trapezoidal piece of metal or wood approximately 2 inches wide and a minimum of 1 inch in depth on the face of the h eader, along the center of the header to form a grooved or keyed joint. With approval of the Engineer, the Contractor may pave beyond the joint location a distance to maintain the line and grade. Saw the construction joint when the concrete has hardened. Drill holes for reinforcing tie bars and epoxy the bars in-place. Place fresh concrete against the previously placed concrete taking care to avoid injury to the edge. Vibrate the concrete to obtain an interlocking joint and preven t a honeycombed face of the joint. The additional concrete, removal of debris a nd other work created by this alternativ e is at the Contractor’s expense. Unless shown otherwise in the Contr act Documents, do not place any constr uction joint within 5 feet of an expansion, contraction or other construction joint.
6.Special Joint Construction. Construct special joints as shown in the Contract Documents or as ordered by the Engineer around drainage, utility and other structures located within the concrete pavement boundaries. Hold temporary forms securely in place dur ing the concrete placement operation.
7.Joint Construction. Construct all joints as show n in the Contract Documents. Repair or replace any curing medium damaged during joint constr uction. Construct joints as follows:
a.Induced Plane of Weakness. The first saw cu t is a relief cut at the proper joint location, approximately ⅛ inch wide and to the full joint depth as shown in the Contract Documents (D/3 ± ¼ inch). Make the relief cut as soon as the concrete has hardened enough so that no excess raveling or spalling occurs, but before any random cracks develop. The sequence of the relief sawing is at the Contractor’s option, provide d all relief sawing is completed before random cracking develops. Use suitable guide lines or devices to cut the joint straight and in the correct location. Repair curing membrane damaged during sawing as directed by the Engineer. See subsection 501.4g.(1) for alternate methods to the first stage sawing.
b.Reservoir Construction. Do not perform widening of the relief joints to full width until the concrete is a minimum of 48 hours old. Delay it longer if the sawing causes raveling of the concrete. If second stage sawing is performed be fore completion of the curing period, maintain the cure by use of curing tapes, plastic devices or other materials approved by the Engineer. Center the joint groove over the relief cut, and saw it to the dimensions shown in the Contract Documents. Should any spalling of the sawed e dges occur that would detrimentally affect the joint seal, patch it with an approved epoxy pa tching compound and allow it to harden before installing the joint material. Make each patch true to the intended neat lin es of the finished cut joint.
8.Cleaning Joints. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-10 (a) Immediately clean freshly cut sawed joints by flushing with a jet of water under pressure and
other necessary tools to remove the resulting slurry from the joint and immediate area. (b) To clean joints, use air compressors equippe d with suitable traps capable of removing all surplus water and oil from the compressed air. The Engineer will check the compressed air for contamination, daily. When contaminated air is found to exist, work will be stopped until suitable adjustments are made, and the air stream is found to be free of contaminants. (c) Just before applying the hot or cold joint sealant, complete a final cleaning by air blasting to clean incompressibles from the joint. (d) Before installing preformed elastomeric joint seals, use water or sandblasting equipment to clean the seal reservoir of the tr ansverse joint a minimum of the vertical height of the installed elastomeric joint material plus ½ inch measured from the pavement surface. Use a multiple pass technique until the surfaces are free of dirt, cu ring compound or any residue that might prevent ready insertion of the seal, or uniform contact with the concrete. (Note: These seals are held in place by compressive forces and friction acting on the faces of th e joint, not chemical bonding as with other joint sealants.) After final cleaning, and immediately before installing the seal, blow out the joint seal reservoir with compressed air until it is free of debris and visible water.
9.Sealing Joints. The joint location, size and configuration is shown in the Contract Documents. Use applicable materials to obtain the required joint sealant configuration. Seal transverse pavement joints with preformed elastomeric compression joint seals, unless shown otherwise in the Contract Documents. Seal longitudinal pavement joints full depth with either a cold applied chemically cured joint sealant or a hot joint sealing compound. Use only 1 type of longitudinal joint sealant on a project, unless otherwise approved by the Engineer. Seal joints before opening to traffic. For opening to construction traffic, see subsection 501.4i.(3)(a) . When using cold applied chemically cured joint sealant, hot joint sealing compound or preformed elastomeric compression joint seals, arra nge for a technical representative of the manufacturer to be present during installation of the joint seal to provide guidance on cleaning, preparation of the joint and installation of the seal. Keep the manufacturer’s technical representative on the project until Contractor and KDOT personnel have been thoroughly trained in the proper installation of the material. The Engineer may waive this requirement for Contractors that are experienced in installing the type and brand of material being used. Provide the Engineer with a résumé of experience for evaluation.
a.Cold Applied Chemically Cured Joint Sealants. Do not seal joints until they are clean and dry, and the pavement has attained the age recommended by the manufacturer of the sealant. Do not apply sealant to damp concrete, or install it during inclement weather. Do not apply joint sealant when the ambient air temperature is below 40ºF, or as specified by the manufacturer. Place the sealer full depth in close conformity with dimensions shown in the Contract Documents. Any deviation will be cause for rejection of the joint until satisfactory corrective measures are taken. Apply the joint sealant by an a pproved mechanical device. Any fa ilure of the joint material in either adhesion or cohesion will be cause for rejection. Repair the joint to the Engineer’s satisfaction. Some cold applied, chemically cured sealants are not self-leveling and will not position properly in the joint under its own weight. Tool the sealant surface as shown in the Contract Documents. Accomplish tooling before a skin form s on the surface. Do not use soap or oil as a tooling aid. After a joint has been sealed, promptly remove all surplus joint sealer from the pavement or structure surfaces. Do not permit traffic over sealed joints until the sealer is tack free, or until debris from traffic can not embed into the sealant. (b) Hot Applied Joint Sealing Compound. Do not s eal joints until they are clean and dry, and the pavement has attained the age recommended by the manufacturer of the joint sealing compound. Install joint sealing compound according to the manufacture’s recommendations. Completely clean out the application unit when changing brands of materials, or if the material exhibits any sign of changes in application characteristics, polymer or oil separation, balling or any signs of jelling. If the application unit contains compatible material from a previous project at start-up, provide the Engineer a certification covering the material in the application unit, including the manufacturer, type, et c. Before start-up, completely clean out any material that can not be identified and certified. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-11 After a joint has been sealed, promptly remove all surplus joint sealer from the pavement or
structure surfaces. Do not permit traffic over sealed joints until the sealer is tack free, or until debris from traffic can not embed into the sealant. (c) Preformed Elastomeric Joint Seals. Concrete that has reached an age that permits proper sawing and cleaning w ithout causing deterioration of the joint edges and joint faces, is considered acceptable for seal installation. Under normal construction procedures, seal transverse joints full width with no splices made in the preformed joint seal. However, under pha sed construction of widenings, where the lanes placed earlier have been opened to traffic, the preformed joint seal may be spliced at the construction joint. When the existing seal is peeled back to saw the construction joint, clean it, reapply the lubricant/adhesive and reinstall as soon as possible. After the new seal is installed, place the longitudinal joint sealan t through the intersection with th e transverse jo int, with the transverse seals butted in. Place the longitudina l sealant to encase and seal the ends of the preformed seals. Install the joint seal with a m achine especially designed to comp ress and install the sealant in an upright position, without cutti ng, nicking, distorti ng or otherwise damaging the seal. Apply lubricant to the concrete or the preformed seal (or both), and install the seal in a substantially compressed condition. Place the top of the seal at a depth below the finished surface of the pavement, recommended by the manufacturer. Use a method of installation such that the jo int seal will not be stretched or compressed longitudinally more than 3% of the length, unless stated otherwise in the manufacturer’s instructions. The method of installation will be checked for stretc hing or compression by comparing the distance between 2 marks on the surf ace of the seal measured before and after the installation. If the check indicates stretching or compression beyond the limits stated above, modify the method of installation to correct the s ituation. The Contractor may proceed slightly out of specification for a short distance under the supervision of the manufacturer’s technical representative, while making corrections and adjustments to return to specification limits. This material may remain in place, provided the st retching does not exceed 5% , and the Contractor makes a good faith effort to correct the problem. Once the machine is in proper adjustment and the installation is proceeding satisfactorily, fu rther checks (approximately every 100 joints) will be made to verify proper installation. Remove any joint seal not conforming to the above stated limits of installation and replace with new material. After being removed for any reason, no seal may be reused.
10.Sawed (Non-Sealed) Joints.
a.Joint Construction. The joint location, size and configuration are shown in the Contract Documents. Use concrete saws to saw all joints a nominal 1/8 inch wide to the full joint depth, D/3± ¼ inch, unless shown otherwise in the Contract Documents. Make the saw cut as soon as the concrete ha s hardened enough so that no excess raveling or spalling occurs, but before any random cracks develop. The sequence of the sawing is at the Contractor’s option, provided all sawing is co mpleted before random cracking develops. Use suitable guide lines or devices to cut the joint straight and in the correct location. (b) Cleaning Joints. Immediately clean freshly cut sawed joints by flushing with a jet of water under pressure and other necessa ry tools to remove the resu lting slurry from the joint and immediate area. Repair curing membrane damaged during sawing and cleaning, as directed by the Engineer. (c) Backer Rod. Install and maintain backer rod (of a size sufficient to prevent debris from entering the joint) in the joint. When major construction traffic is no longer driving on the pavement, and prior to opening to the public, remove the backer rod, and follow with an air blast to remove any debris. (d) Repair of Joints. If the sawed joint is ≥ ¼ inch, seal the joint using Hot Applied Joint Sealing Compound, according to subsections 501.4g.(7) thru (9)(b) . Seal transverse joints the full width of pavement. Seal longitudinal joints the full length of the panel. If the joint can not be properly sealed, see subsection 501.4k . 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-12 (e) Opening to Traffic. When no joints require sealing, disregard subsection 501.4i.(3)(a) , third
bullet and 501.4i.(3)(b) .
f.Side Roads and Entrance Pavement. If the PCCP is designated with sawed (non-sealed joints), construct the side road and entr ance pavement joints according to subsection 501.4g.(10) , unless otherwise specified in th e Contract Documents.
g.Curb and Gutter/Valley Gutter. Unless specified otherwise in the Contract Documents, if the PCCP is designated with sawed (non-sealed) join ts, construct the curb and gutter/valley gutter joints according to subsections 501.4g.(10)(a) thru (c) with the following exception: saw to a depth a minimum of 1 ¼ inches below the surface of the gutter. If the curb and gutter is placed monolithically with the pavement, saw to the same depth as the pavement.
h.Hand Finishing. Hold hand finishing methods to a mini mum. Generally, hand methods of placement and finishing will be permitted as follows: For pavement when a breakdown of some portion of the paving train occurs, making the hand finishing of that portion of the c oncrete already in place necessary. For pavement lanes that may be too narrow or a length too short to accommodate a full paving spread. For all irregular shaped areas. For special approach sections to bridges, widene d portions at bridges, intersections and sections widened beyond traffic lanes. When the dimensions of the work make the use of a complete power operated paving impossible, or impracticable. For uniform width areas or transition width areas using false forms, finish handwork with a mechanical finishing machine or approved vibrating screed, whenever possible. Use spud hand vibrators on any area considered impracticable to vibrate with a vibrating screed. Approved metal or wood floats may be used if needed to help close an open or porous surface condition. Continue the operation of consolidation and screeding or striking off the concrete until the concrete is uniformly consolidated and the surface is true to line, grade and cross-section. After the pavement has been properly struck off, strai ghtedge the pavement for trueness and finish it. Use a burlap drag to remove surface straighte dge marks. The burlap drag may be pu lled by hand, but the results shall be similar to that on the mainline pavement. Manual methods may be used for texturing hand finished pavement areas. Where applicable, the tined texture applies. Use a metal comb with dimensions and spacing shown in subsection 154.7c . Obtain a finished textured surface similar to that produced mechanically. On miscellaneous areas such as entrance pavement, median pavement and gore areas, texturing with the metal comb may be eliminated. Final finish may be attained by the use of a drag that consists of a seamless strip of damp burlap, cotton fabric or other suitable material capable of producing a uniform surface of gritty texture.
i.Protection and Curing of Concrete. Cure the pavement by using burlap, liquid membrane-forming compounds, white polyethylene sheeting, concrete curing bl ankets or reinforced white polyethylene sheeting. Failure to provide proper curing is cause for i mmediate suspension of the concreting operations.
1.Burlap, Concrete Curing Blankets, White Polyethylene Sheeting and Reinforced White Polyethylene Sheeting. Place the curing material on the pavement immediately after the pa vement has been finished, and the concrete has hardened sufficiently to avoid harmful marring of the surface, yet early enough to prevent undue loss of moisture from the concrete. If the pavement become s dry before the curing material is placed, moisten the concrete with a fine spray of water. Dampen burlap and place on the surface. Place burlap-polyethylene blankets with the dampened burlap side down. Keep burlap damp throughout the entire curing period. Lap adjacent units of curing materi als approximately 18 inches. Upon removal of the forms, extend the material to completely cover the full depth of the exposed pavement. Weigh the curing material down usi ng continuous windrows of earth pl aced along the sides and edges of the pavement and transversely across the pavement on the laps to cause the material to remain in contact with the covered surface throughout the curing pe riod. Other methods may be used with approval of the Engineer. Walking on the pavement surface to place the curing material is prohibited. Walking on the curing material is prohibited until the pavement has cure d sufficiently to prevent damage to the surface. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-13 Leave the curing material in place for a minimum of 4 days, unless otherwise dir ected by the Engineer.
Immediately repair any tears or holes appearing in the material during the cu ring period, or replace it with material in good condition. The material may be reused, provided it is kept servi ceable by proper repairs, and if in the judgment of Engineer it will provide water retention during the curing period.
2.Type 2 White Liquid Membrane-Forming Compound. After finishing operations have been completed and immediately after the free water has left the surface, co mpletely coat and seal the surface of the slab with a uniform layer of compound. Apply the compound in 1 app lication at a minimum rate of 1 gallon per 150 square feet of surface. Thoroughly mix the compound at all times during usage. Do not dilute the compound. Daily provide the Inspector documentation of the quantity of curing compound used. Protect the treated surface fro m injury a minimum of 4 days, unless othe rwise directed by the Engineer. If the newly coated film is damaged in any way, apply a new coat of material to the aff ected areas equal in coverage to that specified for the orig inal coat. A minimum of foot traffic will be permitted on the dried film as necessary to properly carry on the work, provided any damage to the film is immediately repaired by application of an additional coat of compound. Immediately after the forms are remove d (fixed form and slip form), coat the entire area of the sides of the slab with compound at the rate specified for the pavement surface, regardless of whether or not further concrete placement will be made against the pavement edge. A pproved hand spray equipment will be permitted only for the application of compound on the sides of the slab, for repair ing damaged areas and for hand finished areas. Repair any damaged areas caused by joint sawing.
3.Opening to Traffic. No motorized traffic is allowed on the pavement until all of the following conditions are met.
a.Construction Traffic Only. The flexural strength of the pa vement shall meet or exceed 450 psi. Determine the flexural strength of the pavement by testing flexural strength specimens utilizing the third point loading method, or by use of a calibrated maturity meter. If flexural strength doe s not meet or exceed 450 psi, obser ve a 10 day curing period before allowing motorized traffic on the pavement. Provi de a strength gain curve of concrete cured at 45°F to justify a curing period of less than 10 days. Provide protection to keep foreign material out of the unsealed joints by an approved method.
b.All Traffic. In addition to subsection 501.4i.(3)(a) , seal the joints according to subsection 501.4g.(9) . The Contractor may, at own expense, increas e the cement content from the minimum shown in SECTION 403 to accelerate the strength gain of the PCCP.
4.Cold Weather Curing. Maintain the concrete pavement at a minimum temperature of 40ºF, as measured along the surface of the concrete, for a minimum of 4 days after placing. When the ambient air temperature is expected to drop below 35ºF anytime during the curing period, take precautions to maintain the concrete temperature. Keep a sufficient supply of approved moisture barrier material, other than liquid curing compound, and suitable blanketing material, such as straw, hay and burla p close by. Be prepared to cover the pavement with a moisture barrier and protect all pavement less than 4 days old with blanketing material. Remove, dispose of and replace concrete damaged by cold weathe r, as determined by the Engineer.
5.Early Strength Concrete Curing. The curing peri od shall conform to the requirements specified for regular concrete pavement in subsection 501.4.i . Construct joints according to the manufacturer’s recommendations for early strength concrete pavement.
j.Cold Weather Limitations. If concrete is placed in cold weather, comply with SECTION 401 .
k.Repair of Defective Pavement Slabs. It is the responsibility of the Cont ractor to repair any spalled, cracked or broken panels as specified hereinafter at no cost to KDOT. Co mpletely remove and replace pavement panels (area between contraction joint and contraction joint) containing both transverse and longitudinal cracks (separating the panel into 4 or more parts) through the full depth of the slab. Properly seal the joints of the repaired or replaced panels.
1.Repair of Spalls. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-14 In no case shall an individual patch of a spall be le ss than 1 square foot with no dimension less than 1
foot. For spalls greater than ¼ inch and less than or equal to ½ inch from edge of the original sawed joint, repair with hot pour. For spalls greater than ½ inch and less than or equal to 1 inch from the edge of the original sawed joint, blast clean and repair with epoxy patch material. For spalls greater than 1 inch from the edge of original sawed joint, repair by making a saw cut a minimum of 1 inch outside the spalled area to a minimum depth of 2 inches. The interior angles formed by the intersection of adj acent sides of the patch shall be a minimum of 60º. When the spalled area abuts a joint, make the saw cut to a depth of 2 inches or 1/6 the slab thickness, whichever is greater. Chip out the concrete between the saw cut and the joint or primary crack to solid concrete. Do not use chipping hammers greater than 15 pounds. Thoroughly clean all loose material from the formed cavity. Apply a coat of an approved concre te bonding epoxy to the dry, cleaned surface of all sides of the cavity, except th e joint. Apply the epoxy by scrubbing the material into the surface with a stiff bristle brush. Place portland cement concrete , epoxy resin concrete or mortar, immediately following application of the epoxy , according to the manufacturer’s recommendations. If the spalled area to be patched abuts a working joint, use an insert or other bond breaking medium during the repair work to maintain working joints. Rem ove and replace major honeycombed areas found after removal of the forms. Removed areas or sections so removed shall be a minimum of 6 feet in length if less than full width of the lane involved. When it is necessary to remove a s ection of pavement, also remove and replace any remaining portion of the slab ad jacent to the join ts that is less than 6 feet in length.
2.Repair of Cracks in New Reinforced, Dowel Jointed PCCP.
a.Transverse and Diagonal Cracks.
i.Full Depth. When a single full-depth transverse crack falls within the middle ⅓ of the panel, no corrective work will be required. Should a second full-depth crack develop within the middle ⅓ of the panel, remove and replace the panel to the nearest planned contr action joint, eliminating both cracks. If the location of the mid-panel full-depth crack is within 6 feet of the boundaries of the area to be repaired, extend the area to be repair ed to include the mid-panel crack. When any portion of a full-depth crack falls outside the middle ⅓ of the panel, remove and replace the portion of panel between the contraction joint and the crack. Make 1 full-depth saw cut parallel to the contraction jo int on the mid-panel side of the crack to be removed. Make another cut in the adjacent pa nel, parallel to the contraction joint, clear of the basket assembly, but not less than 6 f eet from the first cut. Remove the cracked section and basket assembly. Drill holes in both sawed faces, and insert bars to make 2 contraction joints. Use dowels of the same size and spaced the same distance as those shown in the Contract Documents. Drill bar holes ¼ inch ± 0.05 inch larger than the diameter of the bar and fill them with epoxy or grout and insert the new dowel. Support the free ends of the bars parallel to the pave ment surface until the epoxy or grout has set, obtaining proper alignment of the bar. Apply grease or an approved bond breaker to the free ends. If the boundaries of consecutive areas to be repaired are less than 6 feet apart, also remove and replace the areas between the patches. Saw off the longitudinal joint tie bars at the longitudinal joint. Drill holes midway between the existing bars and insert tie bars to make a new tied longitudinal hinged joint. Use tie bars of the same size and spacing as those in the Contract Documents. Drill bar holes ¼ inch ± 0.05 inch larger than the diameter of the ba r and fill them with epoxy or grout and insert new tie bars.
b.Longitudinal Cracks. When a single longitudinal crack falls within a panel, no corrective work will be required. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-15 When a second full-depth longitudinal crack falls w ithin a panel, remove and replace the panel to
the nearest planned contraction joint, eliminating both cracks.
3.Repair of Cracks in both New Non-reinforced Dowel Jointed PCCP and Mainline Plain PCCP.
a.Transverse and Diagonal Cracks.
i.Full Depth. If a maximum of 4 panels per any lane mile has a crack, repair according to SECTION 504 - DOWEL BAR RETROFIT-REPAIR , or remove and replace the pavement. If 5 to 18 of the panels per any lane mile has a crack, repair according to SECTION 504 - DOWEL BAR RETROFIT-REPAIR . When 2 consecutive panels have a crack, remove and replace the panels from cont raction joint to contraction joint. If more than 18 of the panels per any lane mile have a crack, remove and replace the pavement bounded by the cracks in that se gment. Remove and replace until ¼ mile segment has less than 4 panels cr acked, then repair or replace. (ii) Partial Depth. If coring (at no additional co st to KDOT) verifies the transverse cracks are not full depth, repairs may be made by SECTION 505 - TIE BAR INSERTION-REPAIR . (iii) When required or at the Contractor’s option, remove and re place pavement panels containing any transverse or diagona l crack according to the following: Make a full-depth saw cut in the abutting panel nearest to the crack, parallel to the contraction joint, just clear of the basket assembly to allow the existing dowel basket assembly to be completely removed. Make a second saw cut parallel with the contraction joint on the opposite side of the crack away from the contraction joint. For plain PCCP, make the saw cut at the joint nearest to the crack. Make the second saw cut opposite the first cut a minimum of 6 feet from the first saw cut to include the crack. Remove the resulting area. The minimum longitudinal length of a patch is 6 feet. Do not permit a patch to fall within 6 feet of a contraction joint. The maximum distance between doweled/non-doweled contraction joints is 18 feet. Drill holes and insert dowel bars to make new contraction joints with in the vertical faces of both newly created panel ends. Use dow els of the same size and spaced the same distance as shown in the Contract Documents. Drill bar holes ¼ inch ± 0.05 inch larger than the diameter of the ba r and fill with epoxy or portland cement grout and insert the new dowel. Support the free ends of the bars until the epoxy or grout has set to obtain proper alignment of the bar. Apply grease or an approved bond breaker to the free ends. Do not use dowel bars in plain PCCP. Saw off the longitudinal joint tie bars at the longitudinal joint. Drill holes midway between the existing bars and insert tie bars to make a new tied longitudinal hinged joint. Do not place new tie bars within 12 inches of doweled joint. Use tie bars of the same size and spacing as those in the Contract Documents. Drill bar holes ¼ inch ± 0.05 inch larger than the diameter of the bar and fill them with epoxy or grout and insert new tie bars.
b.Longitudinal Cracks. Repair or remove a nd replace pavement panels that contain a single longitudinal crack, accord ing to the following: Repair longitudinal cracks that are within 3 inches of the planned longitudinal joint for their entire length with a partial depth patch as specified for spall in subsection 501.4k.(1) , except make the transverse dimension of the patch 6 inches and saw cuts to D/3 ± ¼ inch. For longitudinal cracks between 3 and 6 inches from the planned longitudinal joint, fill the entire planned longitudinal joint full depth with epoxy through the length of the longitudinal crack. Repair longitudinal cracks that are 6 inches or more from the planned longitudinal joint by removing and replacing pavement panels, or repair pavement by SECTION 505 - TIE BAR INSERTION-REPAIR . 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA) 500-16 Remove and replace pavement panels that contain 2 or more longitudinal cracks.
4.Repair of Cracks in Shoulder Plain PCCP.
a.Transverse and Diagonal Cracks. When a single transverse crack fa lls within a panel and is within 3 feet of the transverse contraction joint, fill the contraction joint according to the Contract Documents and rout and seal the crack. When 2 or more transverse cracks fall with in a panel, remove and replace the panels.
b.Longitudinal Cracks. When a single longitudinal crack falls w ithin a panel, repair pavement by SECTION 505 - TIE BAR INSERTION-REPAIR . When 2 or more longitudinal cracks fall with in a panel, remove and replace the panels.
l.Protection of Pavement from Rain. Before placing PCCP, prepare and submit to the Engineer for approval, a Protection Plan to address the onset of rain during concrete placem ent. As a minimum, the plan shall include protective covering and si de forms available at the project site at all times to protect the surfaces and edges of the newly placed concrete pavement. Polyethylene, burlap or other covering materials ma y be used. Side forms may be of wood or steel and shall have a depth a minimum of the thickness of the pavement. Specify the location of the storage site in order that a review of the protective materials may be conducted by the Engineer. Include the type and amount of protective materials as well as the methods proposed to protect the pavement. When rain appears imminent, stop all paving operations and initiate the Protection Plan. Extend the covering back to the point where the ra in will not indent the surface. Exerci se care to prevent unnecessary damage to the surface with the covering.
m.Pavement Smoothness. Evaluate pavement sm oothness for pay according to SECTION 503 . 501.5 MEASUREMENT AND PAYMENT
a.Plan Quantity Measurement. The quantities of concrete pavement for which payment will be made are the quantities shown in the Contract Documents for the traveled way lanes and the various paved approaches, exits and interchanges, provided the project is constructed essentially to details shown in the Contract Documents. When the Contract Documents have been altered, or when a disagreement exists between the Contractor and the Engineer as to the accuracy of the Contract Document quantities in an y location or the entire project, either party has the right to request and cause the quantities involved to be measured according to subsection 501.5b .
b.Measured Quantities. The quantity to be paid for under this ite m will be the number of square yards of concrete pavement as measured in-pl ace. The width for measurement will be the width of the pavement shown on the typical cross-section of the Contract Documents, additional widening where added, or as otherwise directed in writing by the Engineer. The length will be measured horiz ontally along the centerline of each roadway or ramp.
c.Excavation Included in Contract. On projects where the grading and the pavement or base construction is included in the same contract, the Engineer will not measure additional excavation required to obtain the specified subgrade elevation.
d.Sawing and Sealing Joints. The Engineer will not measure this work for separate payment. All costs of complying with the requirements specifi ed herein are included in the contract price for the concrete pavement in which the joints are located.
e.Quality Control Testing. The Engineer will measure the Contractor’s quality control testing by the square yard of PCCP placed on the project. The Engineer will measure each concrete core when the results from the core information (required for disputed tests) increases payment to the Contractor. All other cores taken as required by this specification are subsidiary to this item. 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA) 500-17
f.Water. The Engineer will not measure water used in dust control on haul roads, around plant installations, etc.
g.Pavement Thickness and Compressive Strength Determination.
1.General. Make the required corrections fo r pavement smoothness before making the pavement thickness determinations. Determination of pavement th ickness and pavement compressive strength for the purpose of establishing pay adjustments will be based on test results from cores taken from each lot of pavement. For mainline pavement, pay adjustments will be made for both thickness and compressive strength. For acceleration lane, deceleration la ne, frontage road, side road and ramp pavement, pay adjustments will be made for thickness, but not compressive strength, unless the Contract Documents specifically require compressive strength pay adjustments. For gore areas, bridge approach slabs, intersection curb returns, entrances, shoulders, medians and widenings, pay adjustments will not be made for thickness or compressive strength, and pavement cores will not be required. Where coring is not required, verify that the thickness of the paveme nt meets or exceeds the Contract Document requirements by use of stringline, survey or other suitable depth measurement. For pavement types not cored for strength, use only concrete mix designs approved for use in the mainline pavement. The Engineer will observe and document the Contractor’s measurement or other means of ensuring the appropriate thickness of the plastic concrete, and the Engineer will verify that only approved mixes are used. Prior to placing any pavement not specifically defined above, reach an agreement with the Engi neer as to the appli cability of pay factors.
2.Lots and Sublots Defined.
a.For mainline and other pavement subject to coring for pay adjustments for both thickness and strength, a lot is defined as the surface area of mainline lane placed in a single day. Normally, divide a lot representing a day’s production into 5 sublots of approximately equal surface area. For high daily production rates, rates exceeding 6000 square yard s per day, the Contractor may choose to divide the day’s production into 2 a pproximately equal lots consisting of 5 sublots each. Prior to taking any core sa mples, notify the Engineer of the decision to divide a day’s production into 2 equal lots. For low daily production rates (and not in an urban PCCP environment), the Contractor may choose to divide the lot into a lesser number of sublots as shown in TABLE 501-1 . When daily production rates are less than 1000 square yards, and not in an urban PCCP environment, combine the day’s production with the next day’s production to form a lot. When a day’s production involves less than 1000 square yards while completing a particular mix design or project, combine with the previous day’s production and treat as a single lot. For low daily production rates less than 1000 squa re yards in an urban PCCP environment, consider each day’s production as a separate lot. KDOT’s representative will core (or have cored) a minimum of two randomly-determined sublots per day; one in the morning and one in the afternoon. Each randomly-determined location w ill be cored for both stre ngth and thickness, and results inserted into the “Urban PCCP” worksheet for pay adjustment. TABLE 501-1: PCCP SUBLOT BREAKDOWN Daily Production Rate in square yards Number of Sublots Under 1000 (Urban) 2 1001 – 2000 3 2001 – 4000 4 4001 or more 5
b.For pavement that is to be cored for thickness only, group each continuous section of acceleration lane, deceleration lane , side road, frontage road and ramp pavement of equal plan thickness and contract unit price into a lot a maxi mum of 5000 square yards in area. Divide each lot into a minimum of 3 sublots of approximately equal surface area. Sublots shall be a maximum 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-18 of 1000 square yards in size. Sample each subl ot in a manner so that each square yard of
pavement has a chance of being randomly selected for coring.
3.Coring. The Engineer reserves the right to ge nerate the random locations. If KDOT plans to generate the random locations, the Contractor will be notified before taking cores for th ickness determination.
a.For mainline and other pavement subject to coring for pay adjustments for both thickness and strength, take 1 core sample having a minimum diam eter of 4 inches from a randomly selected site within each sublot. The Contract or has the option of taking an additional core sample having a minimum diameter of 2 inches from a randomly sel ected site within each sublot for the purpose of making an early determination of the pavement thickness only. Select sites according to the approved QCP. Additionally, take 1 companion core having a minimum diameter of 4 inches per each lot at a randomly selected site as designated by the Engineer. Repair all core holes in a manner approved by the Engineer. Perform all coring for the purpose of determining strength a minimum of 21 days after the pavement has been placed, and in time to determine 28-day compressive strengths. Coring prior to the 21-day minimum will be permitted with approval of the Engineer, when opening to early traffic is desired. If the companion cores will be measured and tested by the MRC, the Engineer will deliver the companion cores to the MRC within 25 days after the pavement has been placed. No initial QC compressive strength data will be accepted for concrete paving that is more than 28 days of age, unless approved by the Engineer.
b.For all other PCCP subject to coring for pay adjustment, thickness only, define the lots prior to placement with the Engineer’s approval. After placement, randomly select each sublot location. Take 1 core sample having a minimum diameter of 2 inches. Repair all core holes in a manner approved by the Engineer. Coring may be performed at any time after all pavement in the lot has been placed.
4.Mark each core with the lot and sublot number fro m which it was selected. Tr ansport the cores to the laboratory as soon as possible and perform the thickness dete rmination. Take 3 caliper measurements on each core at approximately 120º apart. Record these 3 measurements to the nearest 0.01 inch, and average them to represent the height of that core. Do not test 2-inch core samples for compressive strength. Do not measure 4-inch cores for pavement thickness determination if a separate 2-inch core sample was taken in a sublot for that purpose. The measured core height will represent the constr ucted pavement thickness fo r each pavement sublot. The Engineer will witness thickness determinations and initial the Contractor’s documentation. Moist cure the 4-inch cores to be tested for compressive strength as required in KT-49, until they are tested. Perform the 28-day compressive strength testing on the entire length of the core after squaring the ends according to KT-49. The compression m achine shall be capable of testing co res up to and including 12 inches in length. Remove only the excess length that exceeds compre ssion machine capabilities from th e bottom of the cores. Determine length and diameter to the nearest 0.01 inch. Determine the length/diameter ratio (LD), and round the result to the nearest hundredth using the following formula: LD = Length / Diameter After performing the strength test, correct the compressive strength using a correction factor determined by using the appropriate formula in TABLE 501-2 . TABLE 501-2: COMPRESSIVE STRENGTH CORRECTION FACTOR FORMULAS LD Correction Factor LD < 2 2)LD/1(5.19 LD/12.0 95100 LD = 2 1.000 LD >2 )LD(5 110100 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-19 The compressive strength correction factor may also be obtained by using TABLE 501-3 . If a discrepancy
should arise due to rounding numbers or the appropriate value is not shown in the table, the value determined by the above formulas shall govern. TABLE 501-3: COMPRESSIVE ST RENGTH CORRECTION FACTOR LD Compressive Strength Correction Factor LD Compressive Strength Correction Factor 1.00 0.872 2.60 1.031 1.10 0.898 2.70 1.036 1.20 0.920 2.80 1.042 1.30 0.937 2.90 1.047 1.40 0.952 3.00 1.053 1.50 0.963 3.10 1.058 1.60 0.973 3.20 1.064 1.70 0.982 3.30 1.070 1.80 0.989 3.40 1.075 1.90 0.995 3.50 1.081 2.00 1.000 3.60 1.087 2.10 1.005 3.70 1.093 2.20 1.010 3.80 1.099 2.30 1.015 3.90 1.105 2.40 1.020 4.00 1.111 2.50 1.026 Correct the compressive strength de termined during testing by multiplyi ng that amount by the compressive strength correction factor. The Engineer will witness all compressive strength tests for each sublot and initial the Contractor’s documentation. Companion cores will be measured and tested at KDOT’s laboratory to verify the C ontractor’s test results. Supply 28-day compressive strength data to KDOT. Accepta nce of the pavement and pay adjustments will be on the basis of Contractor quality contro l test results on random samples taken from a lot, provided the statistical comparison is favorable. KDOT will routinely compare the varian ces (F-test) and the means (t-test) of the verification test results with the quality control test results for thickness a nd compressive strength as appropriate using a KDOT spreadsheet. The F and t-tests, along w ith the KDOT Spreadsheet us ed to compare the Contr actor’s Quality Control (QC) results and KDOT’s verification ( QA) results, are described in Section 5.2.6-Comparison of Quality Control and Verification Tests, Part V. If KDOT verification test results do not show favorable comparison with the Contractor’s quality control test results , KDOT verification test results will be used for material acceptance, material rejection and the determination of any pay adjustment for thickness and compressive strength. Follow the requirements stated in subsection 501.5h.(6) for failing t-tests. If the Contract or disputes KDOT’s verification test results, and the Contractor and the Engineer cannot mutually agree on the use of KDOT test results to determine pay adjustments, the test results for the lo t in question will be voided. In such case, new cores to represent each sublot will be taken on a 2-for-1 frequency, tested in the presence of the Engineer, and a new pay factor will be calculated using the KDOT spreadsheet. These cores shall be obtaine d in time to determine the 35-day compressive strengths unless approved by the Engineer. If the new pay factor results in the same or less pay due the Contractor than the voided pay factor, no payment will be made for the additional coring. If the new pay factor results in greater payment to the Contractor, KDOT will pay for each a dditional core at the contract set unit price.
5.When the measurement of any core is deficient by more than 1 inch from plan thickness or has a 28-day compressive strength less than 2900 psi, take exploratory cores at a minimum of 10 foot intervals along a line passing through the deficient core and parallel to the center line of the pavement unit. Continue along this line until an exploratory core taken in each dir ection is not deficient in length by mo re than 1 inch, or the compressive strength is a minimum of 2900 psi, depe nding on which case is being investigated . Exploratory cores will be used only to determine the length of pavement in a unit that is to be removed and replaced as provided below. Discard the original core representing the sublot. Randomly select another co re (outside the defective area if left in place) to 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-20 represent the remainder of the sublot and use to compute the pay factor for the lot. All exploratory cores will be
obtained in time to determine the compressive strengths within 35 days from the time the pavement was placed, unless approved by the Engineer. Obtain all cores represen ting the remainder of the sublot and used to compute the pay factor for the lot in time to determine the 35-day compressive strengths, unless approved by the Engineer. When the Engineer determines that deficient paveme nt must be removed, the Contractor is required to remove the deficient areas and replace them with pavement of satisfactory quality, strength and thickness. When it is necessary to remove and replace a le ngth of pavement and one end of the de ficient pavement is less than 10 feet from an expansion, contraction or c onstruction joint, remove and replace th e entire pavement up to the joint. Remove the area so that new joints are a minimum of 10 f eet apart. No additional compensation for materials or labor involved in the removal or replacement of th e deficient concrete pavement will be made.
6.For sublot thickness results greater than 1 inch more than design thickness, change the sublot thickness result to 1 inch more than the desi gn thickness. The KDOT spreadsheet will calculate a new lot mean and sample standard deviation based on the corrected value.
h.Pay Adjustments for Mainline and Other Specified Pavement.
1.General. A single combined pay adjustment for thickness and compressive strength will be made on a lot-by-lot basis and will be based on Contractor quality control test results on all quality control samples representing the lot of the completed pavement provided the statistical check is favorable. Otherwise follow subsection 501.5g.(4) . Compute the combined pay factor ( P) (positive or negative) as shown in Equation 1. Combined Pay Adjustment = P x (the number of square yards included in the lot) x (the contract unit price per square yard) The thickness component of the comb ined pay factor will be based on values determined by using the difference between plan thickness and the measured core sample thickness, and the lower specification limit ( LSL). LSL is defined as 0.2 inch less than plan thickness. The compressive strength component of P will be based on the corrected measured compressive strength of core samples taken from the pavement (see subsection 501.5g.(4) for LD correction). The pay adjustment amount will be adde d or subtracted as Concrete Pavement Composite Pay Adjustment on the pay estimate. Note 1: A lot will normally be comprised of the results of 5 tests performed on a day’s placement of a given pavement type. Lot and sublot size is defined in subsection 501.5g.(2) . Note 2: The sample standard deviation ( S) will be computed as shown in Section 5.2.1-Statistics, Part V.
2.Thickness Quality Index ( QT) Computation. Calculate QT for each lot as shown in 5.2.1, Part V, using the following definitions, and round to hundredths. Where: X is the average measured core length of all QC samples representing a lot, rounded to the nearest 0.1 inch. LSL is the lower specification limit for thickness, and equals plan thickness minus 0.2 inch. S is the sample standard deviation of the measur ed core lengths of all QC samples representing a lot, rounded to the nearest hundredth.
3.Compressive Strength Quality Index ( QS) Computation. Calculate QS for each lot as shown in Section 5.2.1-Statistics, Part V, using the following definitions, and round to the nearest 0.1 inch. Where: X is the average measured compressive strength of all QC core samples representing a lot, rounded to 1 psi. LSL is the lower specification limit for compre ssive strength and is defined as 3900 psi. S is the sample standard deviation of the comp ressive strength of all QC samples representing a lot, rounded to the hundredth.
4.Determination of the Percent within Limits Values. First, use the computed QT to determine the thickness percent within limits value ( PWL T) by locating QT in the left column of the Percent Within Limits (PWL) Table in Section 5.2.1-Statistics, Part V. Select the appropriate ( PWL T) by moving across the selected Q row to the 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-21 column representing the number of samples in the lot. Next, follow the same procedure using the computed QS
value to select the appropriate compressive strength percent within limits value ( PWL S). If either computed QT or QS is a negative value ( X is less than LSL), the Engineer will determine if the material in the lot may remain in place. If the material is left in place, a value of 50.00 is assigned as PWL T or PWL S, respectively. If both QT and QS are negative, assign a value of 50.00 for each PWL component. If either QT or QS is greater than the largest Q shown in the table, a value of 100.00 is assigned as PWL T or PWL S, respectively, or for both should QT and QS both exceed the values shown in the table.
5.Computation of Combined Pay Factor. Compute P for thickness and compressive strength using Equation 1 and round to nearest hundredth. Equation 1: 54.020060.0 ) ( S T PWL PWL P
6.Failing t-test. If the t-test fails, KDOT’s test result will be used to calculate th at particular pay factor for the lot. Follow the procedures given in subsection 501.5h.(4) to determine the pay factor or disposition of the lot. Use the following values to determine QT or QS : Where: X will be KDOT’s test result for the lot. N is equal to the number of Contractor’s sublots. S will be ⅜ inch for thickness and 500 psi for strength. LSL will be as stated in 501.5h.(2) for determining QT, and 501.5h.(3) for determining QS.
i.Pay Adjustments for Pavements Cored for Thickness Only.
1.General. A single pay adjustment for thickness only will be made on a lot-by-lot basis. It will be based on Contractor quality control test results on all quality control thickness samples representing the lot of the completed pavement provided the statistical check is favorable. Otherwise, follow subsection 501.5h.(4) . Compute the thickness pay factor ( PT) (positive or negative) as shown in Equation 2. Thickness Pay Adjustment = PT x (the number of square yards included in the lot) x (the contract unit price per square yard) The thickness component will be based on values de termined by using the difference between plan thickness and the measured core sample thickness, and the lower specification limit ( LSL). The pay adjustment amount will be added or subtracted as Concrete Pavement Composite Pay Adjustment on the pay estimate. Note: A lot will normally be comprised of the results of tests performed on all sublots within a given pavement type. Lot and sublot size for pave ments cored for thickness only is defined in subsection 501.5g.(4) .
2.Determine PWL T as shown in subsection 501.5h.(4) .
3.Computation of Thickness Pay Factor. Compute the pay factor for thickness using Equation 2 and round to nearest hundredth. Equation 2: 27.0 10030.0 ) ( T PWL PT
4.Failing t-test. If the t-test fails, KDOT’s test result will be used to calculate th at particular pay factor for the lot. Follow the procedures given in subsection 501.5h.(4) to determine the pay factor or disposition of the lot. Use the following values to determine QT: Where: X will be KDOT’s test result for the lot. N is equal to the number of Contractor’s sublots. S will be ⅜ inch for thickness. LSL will be as stated in 501.5 i.(2) . 501 - PORTLAND CEMENT CO NCRETE PAVEMENT (QC/QA)
500-22 j. Pay Adjustments for Urban PCCP Environment.
1.General. A single pay adjustment will be made on a sublot-by-sublot basis. The adjustment will be based on a single randomly-selected (by KDOT) core for both strength and thic kness. Compute the pay factor ( PU) (incentive or disincentive) as shown in Equation 3 . The thickness component will be based on values de termined by using the difference between plan thickness and the measured core sample thickness. When the measured core sample th ickness is greater than the plan thickness, the “ thickness” of Equation 3 is positive. When the core thickness is less than the plan thickness, the “ thickness” is negative. The compressive strength com ponent will be based on values determined by breaking the core. Pay adjustment amount will be added or subtract ed on the pay estimate. Remove and replace when values are less than those stipulated in subsection 501.5g.(5) . Maximum individual or combined pay adjustment is 103%.
2.Computation of Urban PCCP Pay Factor. Comput e the pay factor for thickness and strength using Equation 3 and round to nearest hundredth. Equation 3: P U = (PUC + PUT)/2 Where: P UC = 0.0001*(strength) + 0.59; where strength is measured to the nearest 1 psi. PUT = 0.15*( ∆ thickness) + 1.00; where thickness is measured to the nearest 0.01 inch from plan thickness.
3.Computation of Urban PCCP Pay Adjustment. Compute the sublot pay adjustment using Equation 4 . Equation 4 : Urban PCCP Pay Adjustment = ( PU – 1) x (the number of square yards included in the sublot) x (the contract unit price per square yard) This adjustment will be paid for under the bid ite m Concrete Pavement Composite Pay Adjustment.
k.Computations and Rounding. KDOT will use a MICROSOFT EXC EL spreadsheet program to calculate pay adjustments for thickness and compressive strength and to comp are the Contractor’s QC and KDOT’s verification test results. KDOT will provi de a copy of this program to the C ontractor, when requested. Additional information on the program may be obtained from the Bureau of Construction and Materials. It is the Contractor’s responsibility to obtain the software required to run this program. Values computed using equations referenced in this specification may vary sli ghtly from the spreadsheet values due to rounding of numbers. In such cases the numbers computed by the sp readsheet take precedence.
l.General Payment. Payment for "Concrete Pavement", "E arly Strength Concrete Pavement" and "Quality Control Testing" with pay ad justments as specified above is full compensation for the work specified. Payment for "Concrete Core (Set Price)" at the contract set unit price will be paid when the results from the core information (required for disputed tests) increases payment to the Contractor. In the event of overruns or underruns of the Contractor quality control testing, the Engineer will not adjust the contract unit price. Pay adjustments for thickness-only and pay adjustments for thickness and strength combined will use the bid item "Concrete Pavement Composite Pay Adjustment", and will be shown as an added item to the contract. 502 - PORTLAND CEMENT CONCR ETE PAVEMENT (NON-QC/QA)
500-23 Section 502
PORTLAND CEMENT CONCRETE P AVEMENT (NON-QC/QA) Note: PCCP is considered NON-QC/QA when the bid it em Quality Control Testing is not included in the contract. 502.1 DESCRIPTION Construct portland cement concrete pavement (PCCP ) on a prepared subgrade or base course. B I D I T E M S U N I T S Concrete Pavement (* Uniform) (AE) (**) Square Yard Concrete Pavement (* Variable) (AE) (**) Square Yard Early Strength Concrete Pavement (*Un iform) (AE) (**) Square Yard Early Strength Concrete Pavement (* Variable) (AE) (**) Square Yard * Thickness ** No entry denotes PCCP with mesh and dowel assemblies. "Plain" denotes PCCP without mesh and dowel assemblies. "NRDJ" denotes non-reinforced dowel jointed PCCP. "Br App" denotes bridge approach pavement. 502.2 MATERIALS Provide materials that comply with the applicable requirements. Concrete and Grout ................................................................................. SECTIONS 401 & 403 Aggregates for On Grade Concrete ......................................................... SECTION 1116 Reinforcing Steel ..................................................................................... DIVISION 1600 Epoxy Coated Steel Bars for Concrete Reinforcement ........................... DIVISION 1600 Joint Seal ants ........................................................................................... DIVISION 1500 Expansion Join t Fille r ............................................................................. DIVISION 1500 Concrete Curing Material s ...................................................................... DIVISION 1400 Preformed Elastomeric Co mpression Joint Seals .................................... DIVISION 1500 Cold Applied Chemically Cured Joint Sealant ........................................ DIVISION 1500 Hot Type Joint Sealing Compound ......................................................... DIVISION 1500 Backer Rod……………………………………………………………… DIVISION 1500 Epoxy Resin-Base Bonding Sy stem for Concrete ................................... SECTION 1705 Bond Breaker .......................................................................................... SECTION 1718 502.3 CONSTRUCTION REQUIREMENTS
a.Preparation of the Subgrade. Before placing any surfacing materi al on any section, complete the ditches and drains along that section to effectively drain the highway. Trim the base or subgrade to the line, grade and typical cross-section as shown in the Contract Documents. Maintain the subgrade or base to the as-constructed condition under other bid items, repairing any encountered def ects to the specifications of those bid items. Maintain the subgrade surface to readily drain at all times. Protect the subgrade fro m damage when handli ng materials, tools and equipment. Do not store or st ockpile materials on the subgrade. Do not place material or lay pavement on a frozen or muddy subgrade, or when it is raining or snowing. Lightly spray the subgrade or base with water to obtain a thoroughly mois tened condition when the concrete is deposited on it. Do not puddle water on the grade. Do not deposit any material until the subgrade or base has been checked and approved by the Engineer. 502 - PORTLAND CEMENT CONCR ETE PAVEMENT (NON-QC/QA)
500-24 b. Slip Form Paving. When paving is performed with a slip fo rm paving unit, use equipment as described
in subsection 154.5 . Pave 24-foot wide mainline paveme nt in a single operation. Do not exceed 24-foot paving width in a single operation except as follows: The Contractor may pave a maximum of 2 lanes plus a 6-foot shoulder (30 feet maximum) in a single operation. For pavements of 3 lanes or more, pave a minimum of 2 lanes mainline (with the option of including a single shoulder for a maximum of 30 feet) in a single operation. Approval will be based on satisfactory performance of the Contractor’s operation. Place ramps and auxiliary lanes/shoulders as shown in the Contract Documents. Once the paving operation has started, provide adequate equipment and supply of materials to maintain continuous placement for any given working period. Keep all conc rete conveying equipment clean. Do not apply any tractive forces to the slip form paver, except that which is controlled from the machine. Trim to grade the subgrade or surf ace of the base over which the tracks of the paver will travel. Do not disturb this surface with other equipmen t. If the equipment or method of opera tion requires the subbase to be wider than shown in the Contract Documents, place additional material to provide an adequate surface for the tracks of the paver. Upon completion of the paving ope rations, remove or repair any base material damaged by the slip form paver’s tracks. All necessary constructi on and removal of this additional base ma terial is subsidiary to other items of the contract. Operate the paver continuously, stoppi ng only when absolutely necessary . If the forward motion of the paver is stopped, immediately stop the vibrator and tamping elements. Deposit the concrete on the grade in successive batche s to minimize re-handling. Place concrete over and against any joint assemblies so the joint assembly is retained in its correct position. Spread the concrete using approved mechanical spreaders to prevent segregation and separation of the materials. After striking the concrete off with the spreader, l eave sufficient concrete in place to allow the final shaping by the use of screeds, templates and pans, de pending on make, model and type of machines approved for use in the paving train. Adjust the paving units to meet the required final cross-section, minimizing the need to carry back concrete to fill voids or depressions. Adjust each screed or te mplate so a uniform roll of concrete extends the full length of the screed or template and a llows just enough concrete to pass under the unit to properly feed the next machine. Do not shove large volumes of concrete with the screed or template. Adjust the screed or template to maintain a uniform cross-section. Use multiple spreaders for single and multiple lift opera tions. Place concrete ahead of the initial spreader strikeoff no more than 30 minutes ahead of the final spreader strikeoff. The use of any paving machine in the paving train is contingent on its ability to finish the pavement satisfactorily to the required grade, s ection and specified degree of consolida tion. The Engineer may at any time require the adjustment, repair or replacement of the machine for unsatisfactory performance. Correct any edge slump of the pavement in excess of ¼ inch, exclusive of edge rounding, before the concrete hardens. Excessive edge slumping will be sufficient reason to discontinue paving until machinery (or mix) is properly adjusted or removed from the project. When the machine finishing has been completed, check the surface with a straightedge a minimum of 10 feet in length before texturing. Operate the straightedge parallel to the pavement centerline, starting at the center and progressing outward. Advance in successive stages of less than ½ the length of the straightedge. At the Contractor’s option, this requirement may be eliminated when smoothness is to be determined by the profilograph.
c.Placing Reinforcement. Place pavement reinforcement at th e locations shown in the Contract Documents. Use a sufficient number of approved metal, bar supports or pins to hold all dowel bars and tie bars in proper position as required by th e Contract Documents. Install tie bars pe rpendicular to the concrete face being tied together. Do not use stones, concrete or wood to support the reinforcement. Joint tie bars may be installed mechanically if appr oved by the Engineer. The satisfactory placement of the bars depends on the ability of the Contr actor’s operation to place and maintain th e bars in their true position. When satisfactory placement is not obtained by mechanical means, the Engineer may require the tie bars be installed ahead of placing the concrete, and that they be securely held in their exact position by staking and tying. Do not install dowel bars mechanically. Install th e dowel bars ahead of placing the concrete, and hold them securely in their exact position by staking or tying.
Source: Kansas Standard Specifications for State Road and Bridge Construction, 2015 Edition. Pages 173–218 of 978.