501Portland Cement Concrete

501.01.01 General. This work consists of proportioning, placing, and curing Portland cement, aggregates,

water , and when specified, admixtures. MATERIALS

501.02.01 General. Materials shall conform to the following Sections:

Portland Cement ................................ ................................ ................................ ................................ ................................ ...... Section 701 Concrete Curing Materials and Admixtures ................................ ................................ ................................ .............................. Section 702 Aggregates for Portland Cement Products ................................ ................................ ................................ ............................... Section 706 Water ................................ ................................ ................................ ................................ ................................ ....................... Section 722

501.02.02 Aggregates. Produce and stockpile adequate quantities of aggregate sufficiently in advance of

construction operations as to permit sampling, testing , and mix designs before use. Give not less than 32 days notification in adva nce of use of the proposed sources of materials and make arrangements for the Engineer to obtain samples as required for testing purposes. When requested, exceptions to the above requirement may be granted in writing when the aggregate source has been previously tested within the past one year and accepted by the Department. When producing Portland cement concrete, use the same aggregates used in the approved mix design. Store aggregates in stockpiles sufficiently removed from each other to prevent th e materials at the edges of piles from becoming intermixed, and to allow sampling by heavy equipment. Use lightweight aggregates specified in Subsection 706.03.02 only where lightweight concrete is specified or is approved. For Class E and EA concrete, u se a three aggregate system consisting of a blend of two Coarse Aggregates from Subsection 706.03.01 and Fine Aggregate conforming to Subsection 706.03.03. If approved, the 25 mm (1 in.) combined grading limits may be used in lieu of the 19 mm (3/4 in.) combined grading limits. Use American Concrete Institute, Manual of Concrete Practice, Guide 302.1R -04, Section 5.4.3 Combined Aggregate Grading to optimize the combined aggregate grad ing within the grading limits in Subsection 706.02.01. Submit the results with the mix design. Provide necessary means to obtain an aggregate sample from the batch plant conveyor belt. Construct the sampling device so representative samples may be taken a s required. Deliver the samples by mechanical means to a point on the ground or other satisfactory safe and accessible location. If two consecutive sieve analysis results are out of specification, reprocess the failing stockpile or stockpiles. If three co nsecutive sieve analysis results are out of specification, the stockpile or stockpiles will be rejected. Once rejected material has been replaced, provide test results indicating the new material is within specification. The gradation requirements represe nt the extreme limits in determining the suitability of material. Maintain the gradation from any one source, for any one contract, at a uniformity such that variations in the fineness modulus will not exceed ± 0.2 from the “Base Fineness Modulus.” The “Ba se Fineness Modulus” shall be the average of the most recent 10 fineness modulus values (or the average of all preceding values if less than 10 have been completed) from any one source, for any one contract. Fine aggregate from any one source, for any one contract, having a variation in fineness modulus of more than 0.2 as prescribed above will be rejected or may be accepted subject to approved changes. 501 PORTLAND CEMENT CONCRETE 208 501.02.03 Cement. Use Type V cement with a minimum of 20% pozzolan by mass in all concrete. In lieu of this requirement, Type II cement with a minimum of 20% pozzolan by mass or Type IP cement may be substituted therefore. For Class S and SA concrete, the maximum shrinkage requirement of 0.06% in 28 days air dry after 28 day wet cure (ASTM C157) shall appl y if the amount of cement exceeds 450 kg/m3 (752 lb/yd3), excluding drilled shaft applications.

501.02.04 Admixtures. Use admixtures according to manufacturer’s recommendations and as incorporated

into the approved mix design. Do not add water to the con crete once the water reducing admixture has been incorporated into the mix. Do not use admixtures that were not incorporated into the approved mix design. If approved, a n exception may be allowed for an admixture intended to retard setting time. Do not u se admixtures containing chlorides as CL – in excess of 1% by mass in prestressed concrete. If admixtures are used to reduce the water -cement ratio or to accelerate setting time, use them at the rate of dosage specified on the mix design. When a Type F High Range Water Reducer is used, the slump requirements of Table I of Subsection 501.0 2.05 are hereby waived and the slump of the concrete after the admixture is added shall not exceed 200 mm (8 in.). Dispense chemical admixtures in liquid form. Use all low and mid -range water reducing admixtures (Type A, D, and E) only in dosages as specified on the mix design. Use high range water reducing admixtures (Type F and G) designated on the mix design which may be varied within the manufacturer's recommendati ons to achieve the desired slump within the specified limits. When water -reducing agents or water -reducing retarders are used, do not exceed the dosage of the admixture which will result in an increase in the drying shrinkage of the concrete in excess of 20% when used in precast, prestressed concrete; 10% when used in cast -in-place prestressed concrete; 10% when used in cast -in- place reinforced concrete; or 3% when used in non -reinforced concrete pavements. Do not use set retarders in dosages greater than those recommended by the manufacturer, nor more than that needed to obtain the desired retardation. Store pozzolan in separate weather -tight facilities. In lieu of the 20% minimum addition of pozzolan, slag cement will be permitted as a mineral admixtur e. Use a minimum of 35% slag cement. Class F pozzolan may be used in conjunction with slag cement at a rate of 15% by mass of the total cementitious material. The maximum total mineral admixture substitution shall be 50% of the mass of the total cementitio us material. Silica fume conforming to Subsection 702.03.06 may be used to replace 3% to 7%, by mass, of the total cementitious material. After the concrete has been batched and delivered to the project, only one attempt may be made, by adding approved a dmixtures, to bring the slump and air content into specification as specified in Table I of Subsection

501.02.05 Do not add water to the mix after water reducing admixtures are added onsite.

PORTLAND CEMENT CONCRETE 501 209 501.02.05 Concrete Making Properties. Portland cement concrete will be tested according to the following test methods: Test Test Method Compressive Strength of Molded Concrete Cylinders (a) ................................ ................................ ................................ .......... ASTM C39 Making and Curing Test Specimens in the Laboratory ................................ ................................ ................................ ............ ASTM C192 Making and Curing Concrete Compression Test Specimens in the Field ................................ ................................ ................... Nev. T428 Unit Weight , Volume and Cement Factor ................................ ................................ ................................ ................................ ... Nev. T435 Air Content (b) ................................ ................................ ................................ ................................ .............................. Nev. T431 or T432 Aggregate Correction Factor ................................ ................................ ................................ ................................ ................... ASTM C231 Specific Gravity and Absorption of Coarse Aggregate ................................ ................................ ................................ ................ Nev. T492 Specific Gravity and Absorption of Fine Aggregate ................................ ................................ ................................ .................... Nev. T493 Slump (c) ................................ ................................ ................................ ................................ .............................. Nev. T438 or Nev. T439 Slump Flow ................................ ................................ ................................ ................................ ................................ ................ Nev. T417 Passing Ability (J -Ring) ................................ ................................ ................................ ................................ .............................. Nev. T418 Visual Stability Index, VSI ................................ ................................ ................................ ................................ ........................... Nev. T417 Coring Concrete ................................ ................................ ................................ ................................ ................................ ....... ASTM C42 Length of Drilled Cores ................................ ................................ ................................ ................................ ........................... ASTM C174

501.03.01 Equipment. Maintain the equipment in good condition and adjustment.

Provide adequate internal vibrating equipment, including power, to enable fabrication of concrete cylinders for testing purposes. Furnish internal vibrators with rigid or f lexible shafts, preferably powered by electric motors, capable of operating at a frequency of 7,000 vibrations per minute or greater. The outside diameter or the side dimensions of the vibrating element shall be at least 19 mm (3/4 in.) and not greater tha n 38 mm (1 1/2 in.). The length of the shaft shall be at least 600 mm (24 in.).

501.03.02 Protecting and Sampling Cement. Provide suitable means of storing and protecting the cement

against moisture or other injurious effects. Sacked or bulk cement which has become partially set or which contains lumps of caked cement will be rejected and shall be immediately removed from the work site. Do not mix different brands of cement during use or in storage, nor use alternately in any one structure. Use the same b rand and kind of cement in a given structure above the ground line. Pile the sacked cement as to permit access for tally, inspection, and identification of each shipment. Obtain from the cement company , a certificate stating that the cement delivered to the work complies with the specifications for the type of cement specified for use. Deliver 2 copies of the certificate which is dated, signed, and indicates the quantity of shipment. Upon receipt of the Certificate of Compliance, the Engineer may permit the use of the cement. When a Certificate of Compliance is not furnished, do not use the cement in the work until the material has been tested and approved. Allow 14 days for the Department to test previously approved brands of cement in common use, and 2 8 days to test new or previously unapproved brands of cement. If it is determined by subsequent laboratory tests of mill or field samples that the cement does not comply with the specifications, discontinue use of mix designs containing the failing cement until tests can be made on each lot of cement delivered. Remove from the work any cement not conforming to the specifications, or damaged by exposure to moisture. 501 PORTLAND CEMENT CONCRETE 212 501.03.03 Storage of Aggregates . Perform the handling and storage of aggregates as to pre vent segregation or contamination by foreign materials. Discontinue storage or transportation methods which cause the segregation, degradation, or the combining of material. If the aggregate for a concrete mixture is to be a composite material from 2 or m ore sources, proportion material from respective sources separately or blend by methods which will maintain the gradation required. Before use, add moisture to the aggregate stockpiles to provide a fully saturated condition ensuring complete absorption of water. As necessary before batching, stop the application of water to the stockpiles so that the aggregates are at or above saturated surface dry condition when they are incorporated into the batch. Test the aggregates to determine the amount of free wate r on the aggregate and adjust the addition of mix water accordingly during batching. Do not use aggregates that show visible separation of water and aggregates during transportation from the stockpile to the batch plant.

501.03.04 Proportions. Batch concr ete to within the following tolerances from the approved mix design:

Constituent Tolerance Cement ................................ ................................ ................................ ................................ ................................ .............................. ± 1% Water Holdback Water ................................ ................................ ................................ ................................ ................................ ............ - 10% Additional Water ................................ ................................ ................................ ................................ ................................ ............ + 1% Mineral Admixture ................................ ................................ ................................ ................................ ................................ .............. ± 1% Liquid Admixture* ................................ ................................ ................................ ................................ ................................ .............. ± 5% Individual Aggregate Weight ................................ ................................ ................................ ................................ ........................... ± 1.5% Combined Aggregate Weight ................................ ................................ ................................ ................................ ............................. ± 1% Unit Weight ................................ ................................ ................................ ................................ ................................ ... ± 50 kg/m3 (3 lb/ft3) * This tolerance does not apply to addition of admixtures for air entrainment and high range water reducers intended to increase slump.

501.03.05 Proportioning Methods. Use aggregate bins that conform to either of the following:

501.03.06 Mixing. Attach permanent legible plates on mixers showing manufacturer’s rated capacity, mixing

speeds , and serial number. Mixers may be stationary mixers or truck mixers. Agitators may be truck mixers operating at agitating speed or truck agitators. Attach a metal plate or plates on each mixer and agitator in a prominent place on which is plainly marked the various uses for which the equipment is designed, th e manufacturer’s guaranteed capacity of the drum or container in terms of the volume of mixed concrete and the speed of rotation of the mixing drum or blades. Furnish samples of the fresh concrete and provide safe and satisfactory facilities for obtaining the samples. Concrete mixers may be of the revolving drum or the revolving blade type. Operate the mixing drum or blades uniformly at the mixing speed recommended by the manufacturer. Maintain the temperature of materials as charged into the mixer such that the temperature of the mixed concrete at the time it is placed in final position is not less than 10 °C (50 °F) nor more than 32 °C (90 °F) as specified in Subsection 501.03.09 (b). Aggregates and water used for mixing shall not exceed 65 °C (150 °F). Mix concrete for structures for a period of not less than 1 minute nor more than 5 minutes after all materials, including water, are in the mixer. Batch and charge cement into the mixer by means that will not result either in loss of cement due to the e ffect of wind, or in accumulation of cement on surfaces of conveyors or hoppers, or in other conditions which reduce or vary the required quantity of cement in the concrete mixture. Do not exceed 30 minutes total elapsed time between the intermingling of damp aggregates and cement and the start of mixing. Do not use mixers and agitators which have an accumulation of hard concrete or mortar or worn blades. Completely discharge wash water from the drum or mixing container before the succeeding batch is introduced. 501 PORTLAND CEMENT CONCRETE 214 When central -mixed concrete is furnished and non -agitating hauling equipment is used for transporting concrete to the delivery point, for Portland cement concrete pavement, complete discharge into the concrete paver within 45 minutes after the ad dition of the cement to the aggregates. When mixing at the site of the work , use mixers of the paving or stationary type. Do not exceed the rated capacity of mixers as determined by the manufacturer. Ready -mixed concrete includes central -mixed, shrink -mixed, and transit -mixed concrete. Shrink -mixed concrete is concrete that has been mixed partially in a stationary mixer and the mixing completed in a truck mixer. Do not exceed the rated capacity in truck mixers and truck agitators as determined by the manufacturer. Store approved cement at the concrete plant in such a manner that it can be identified and kept separate from other cement. Transport ready -mixed concrete for structures in truck mixers or truck agitators. The mixer, when loaded to capacity, shall be capable of combining the ingredients of the concrete into a thoroughly mixed and uniform mass within the specified time, and of discharging the concrete with a satisfactory degree of uniformity. The agitator, when loaded to capacity, shall be capa ble of maintaining the mixed concrete in a thoroughly mixed uniform mass and of discharging the concrete with a satisfactory degree of uniformity. Mixers and agitators will be examined periodically for accumulation of hardened concrete or mortar or to wea r of the blades. If accumulation or wearing is detected, correct the faulty equipment before further use. Equip truck mixers with electrically or mechanically actuated revolution counters by which the number of revolutions of the drum or blades may be rea dily verified. Use counters of the continuous -registering, non - resettable type, which accurately register the number of revolutions, and mount on the truck mixer so that the Engineer may safely and conveniently inspect them from alongside the truck. When a truck mixer is used, mix each batch for not less than 70 nor more than 100 revolutions of the drum or blades at the rate of rotation designated by the manufacturer of the equipment as mixing speed. If additional mixing is done, mix at the speed designate d by the manufacturer of the equipment as agitating speed. Do not exceed a total of 320 revolutions from the time of initial batching to complete discharge of delivered concrete. When shrink -mixed concrete is furnished, all requirements for transit -mixed concrete shall apply. No credit in the number of revolutions at mixing speed will be allowed for partial mixing in a central plant. Upon delivery to the job site, if an admixture or additional water is incorporated into the concrete, revolve the drum not less than 45 revolutions at mixing speed or until a homogeneous mixture is obtained. Control the rate of discharge of mixed concrete from truck mixer -agitators by the speed of rotation of the drum in the discharge direction with the discharge gate fully o pen. When truck mixer or truck agitator is used for transporting concrete that has been completely mixed in a stationary mixer, mix during transportation at the agitating speed designated by the manufacturer of the equipment. When a truck mixer or agitat or is used for transporting concrete, deliver the concrete to the site of the work and complete discharge within 90 minutes after the introduction of the mixing water to the cement and aggregates, or the introduction of the cement to the aggregates. In hot weather or under conditions contributing to quick stiffening of the concrete, a delivery time of less than 90 minutes may be required. When a truck mixer is used for the complete mixing of the concrete, begin the mixing operations within 30 minutes after the cement has been intermingled with the aggregate. A request in writing may be submitted for approval to exceed the specified 90 minute time limit for the discharge of the concrete. Include the maximum time limit requested, the name and dosage rate of t he admixture, and the identification of the mix design with which the admixture will be used. Design the admixture specifically for the purpose of controlling slump loss and temperature increase, by stopping or slowing the rate of hydration of the cement. A new mix design and/or a new trial batch may be required before approval. The request will be considered only when the mixing plant is such a distance from the site of work that it is not practical to have the mixed concrete delivered and placed within th e 90 minute time limit. PORTLAND CEMENT CONCRETE 501 215 All other requirements of the specifications shall remain in effect when using the admixture, including slump and temperature requirements. If the mixing plant is so located from the site of the work that is not practical to have m ixed concrete delivered and placed in forms within the time limit specified, submit a proposal for the delivery method of the concrete. Use a concrete supplier and batch plant that has sufficient plant capacity and transport vehicles to insure continuous delivery at the rate required. Provide a rate of delivery of concrete such as to allow for the proper handling and placing of concrete. Do not allow an interval of more than 45 minutes between any 2 consecutive batches or loads. Maintain a delivery and pla cing rate of not less than 6 m3 (8 yd3) of concrete per hour on work other than new bridge decks . Maintain a delivery and placing rate of not less than 6 m (20 ft) per hour on new concrete bridge decks. For Class S and SA concrete, place each successive ba tch within a maximum interval of 20 minutes. If failing to adhere to this requirement , work will be shut down for the remainder of the shift. If so ordered to shut down, make a construction joint at the location and of the type directed. After mixing of r eady -mixed concrete has been completed, agitate it continuously at agitating speed until it has been discharged from the drum. Concrete with unmixed lumps of cement in the mixed product will be rejected. Use a batch ticket system for recording each load of concrete delivered to the project. Batch tickets shall include the ticket number, date and time of batching, weight of each constituent used (actual and design), and aggregate moisture (free and absorbed). Issue tickets to the truck operator at the plan t and deliver them to the Department inspector at the site of the work. Loads that arrive at the jobsite without batch tickets will be rejected.

501.03.07 Retempering. Mix concrete only in such quantities as are required for immediate use and place

before initial set has taken place. Waste concrete in which initial set has begun. Do not retemper concrete.

501.03.08 Curing. Cure concrete for the length of time hereinafte r specified.

Cure all bridge decks and approach slabs according to (d) Bridge Deck Curing. Commence curing immediately upon completion of the finish. In the event that the application or placement of the curing medium is delayed, fog as described below u ntil curing method is applied. Use fogging equipment capable of applying water through an atomizing nozzle in the form of a fine mist, not a spray. The equipment may use water pumped under adequate high pressure, or a combination of air and water pumped u nder high pressure. Use equipment sufficiently portable for use in the direction of any prevailing wind. Adapt equipment for intermittent use as directed to prevent excessive wetting of the concrete.

501.03.09 .

After the wet curing period, remove the wet curing materials and apply curing compound according to (a) Curing Compound Method . Maintain the moisture content of the surface of the deck until the curing compound is applied. The application rate of the bridge deck curing compound, at any point, shall be 0.30 ± 0.05 L/m2 (1 gal/135 ft2 ± 20 ft2). Equip power operated spraying equipment for application of curing compound with an operational pressure gage and means of controlling the pressure. PORTLAND CEMENT CONCRETE 501 217 If the bridge deck cracks, the Department will determine the appropriate repair method. Visual inspection, coring, or other methods may be used in the analysis. Epoxy flooding of the deck, epoxy injecti on of the cracks, a multilayer overlay, a polymer concrete overlay, another repair method, or a combination of repair methods may be required depending on the type and severity of the cracks. Submit a plan for accomplishing the required repair method for a pproval.

501.03 09 Weather Limitations. (a) General. Evaluate weather conditions prior to decid ing whether or not to

begin the pour. Before any concrete is placed, have adequate provisions readily available as approved, to protect the concrete from any im pending weather conditions. In case precipitation should occur after placing operations have started, provide ample covering to protect the work. Stop the placing of concrete before the quantity of precipitation is sufficient to cause a flow or to wash the surface. The temperature of any surface that comes in contact with fresh concrete shall be at least 4 °C (40 °F) and maintained at 4 °C (40 °F) or above during the placement of concrete. The temperature differential between the coldest or warmest surface and the fresh concrete shall not be more than 17 °C (30 °F).

501.05.01 Payment. Portland cement concrete will be measured and paid for by the provisions specified in

the various Sections of these specifications covering construction requiring concrete. 219 SECTION 502 CONCRETE STRUCTURES DESCRIPTION

502.01.01 General. This work consists of furnishing and placing Portland cement concrete in bridges, approach

slabs, culverts, headwalls, retaining walls, barrier rail, and other designated structures. This work also consists of furnishing and installing expansion joints and elastomeric bearing pads. MATERIALS

502.02.01 General. Material shall conform to the following Sections:

Portland Cement Concrete ..................................................................................................................................................... Section 501 Concrete Curing Materials and Admixtures ............................................................................................................................ Section 702 Joint Material .......................................................................................................................................................................... Section 707 Miscellaneous Metal ............................................................................................................................................................... Section 712 Reinforcement ........................................................................................................................................................................ Section 713 Elastomeric Bearing Pads ...................................................................................................................................................... Section 725 Use concrete of the class or classes designated in the proposal and on the plans. Unless otherwise specified, use Class A or Class AA concrete. Class D may be substituted for Class A concrete or Class DA may be substituted for Class AA concrete. CONSTRUCTION

502.03.01 Depth of Footings. Consider the elevation of the bottoms of footings, as shown on the plans, as

approximate only and changes may be ordered in writing in dimensions or elevations of footings as may be necessary to secure a satisfactory foundation.

502.03.02 Forms. Build forms mortar tight and of sufficient rigidity to prevent distortion due to the pressure of

the concrete and other loads incidental to the construction operations. Thoroughly clean forms previously used of all dirt, mortar, and foreign matter before being reused. Thoroughly coat all inside surfaces of the forms with an approved coating or form oil before concrete is poured in forms. Do not use coating or form oil which leaves film on the surface of the form that can be absorbed by the concrete. When required and immediately before placing concrete, thoroughly wet the forms with water. Submit detailed plans of form work for examination when requested. If such plans are not satisfactory, make the necessary changes as required. Be responsible to obtain satisfactory results with the plans submitted or corrected. Construct the forms to be substantial and unyielding and design so that the finished concrete will conform to the proper dimensions and contours. Design forms to take into account the effect of vibration on the concrete as it is placed. Fillet forms at all exposed corners unless corners are rounded as hereinafter provided. Use triangular molding for fillets with 2 equal sides. In general, the width of the equal sides of moldings shall be 19 mm (3/4 in.); for massive work, such as heavy pier copings and columns, the width shall be 38 to 50 mm (1.5 to 2 in.). Top edges of walls may be filleted or rounded as hereinafter provided for curbs. Round top edges of curbs and slabs with an edging tool to a radius of 12.5 to 19 mm (1/2 to 3/4 in.). When concrete is placed in excavation, provide forms for all vertical surfaces unless otherwise permitted. Provide ports in high, thin walls to permit thorough cleaning before placing concrete. Do not place forms or falsework supports on recently constructed footings or pile caps until the concrete has attained 80% of the required 28 day strength. If the forms develop any defects, such as bulging or sagging after the concrete has been poured, correct that portion of the work in a satisfactory manner. During the erection and after the completion of the forms, protect them in such manner as to preclude shrinkage, warping, curling, and distortion.