195produce a mortar having a compressive strength of at least 90 percent of a mortar of the same design using distilled water. The Engineer will permit the use of wash water from hydraulic cement concrete mixer operations in the concrete mixture provided it is metered and it is 25 percent or less of the total water required. The total water shall conform to the acceptance criteria of ASTM C1602, Tables 1 and 2. The Contractor shall use a uniform amount of wash water in consecutive batches, with subsequent admixture rates adjusted ac - cordingly to produce a workable concrete conforming to the Specification requirements for the concrete mixture. SECTION 217—HYDRAULIC CEMENT CONCRETE
217.01 Description
These specifications cover materials, design criteria, mixing, and testing procedures for hydraulic cement concrete.
217.02 Materials
Hydraulic cement concrete shall consist of hydraulic cement, fine aggregate, coarse aggregate, water, and admixture(s) mixed in the approved proportions for the various classes of concrete by one of the methods designated hereinafter. The Contractor shall be responsible for the quality control and condition of materials during handling, blending, and mixing operations and for the initial determination and necessary adjustments in the pro - portioning of materials used to produce the concrete.
a.Cementitious materials shall be a blend of mineral admixtures and portland cement. In overlay concretes, expansive hydraulic cement is permitted in lieu of portland cement. Portland cement (Types I, II, III), blended cements or expansive cement (Type K) shall comply with Section 214. Blended and Type K cements shall be used only as approved by the Engineer unless otherwise specified. Flyash, ground granulated iron blast-furnace slag (GGBFS), silica fume or metakaolin shall conform to Section 215. The table below lists the minimum percentage of specific mineral admixtures, required by mass, as a portion of the cementitious material depending on the alkali content of the cement. Any other mineral admixture or any other amount or combination of min - eral admixtures may be used if approved by the Engineer. The fly ash content shall not exceed 30 percent for Class F, the ground granulated blast-furnace slag content shall not exceed 50 percent and the silica fume content shall not exceed 10 percent as a portion of the cementitious mate - rial unless approved by the Engineer. Class C Flyash or other mineral admixtures may be used provided the Contractor demonstrates that the percent usage of Class C Flyash or other mineral admixtures have a maximum expansion of 0.15% at 56 days according to ASTM C227 using borosilicate glass as aggregate. Minimum percent mineral admixtures required by mass of cementitious material as a portion of the total cementitious materials and is based upon the alkali content of the cement in accordance with the following:217.02 196 Mineral Total Alkalies of Cement is Total Alkalies of Cement is Admixtures less than or equal to 0 .75% greater than 0 .75% and less than or equal to 1 .0% Class F Flyash 20% 25% GGBF Slag 40% 50% Silica Fume 7% 10% Metakaolin 7% 10%
b.Formulated latex modifier shall be a nontoxic, film-forming, polymeric emulsion of which 90 percent of the nonvolatiles are styrene butadiene polymers. It shall be homogeneous and uniform in composition and free from chlorides. Latex modifier shall conform to the chemical and physical properties specified hereinafter when tested in accordance with FHWA’ s Report RD-78-35. Initial approval of the modifier by the Department will be based on an analysis of the results of tests performed by an independent laboratory. After initial acceptance, material will be accepted upon certification subject to periodic testing by the Department. A copy of the initial test report shall be submitted to the Department and shall show the following chemical and physical properties: Property Value Butadiene content (%) 30-40 Solids (%) 46-53 pH 8.5-12 Coagulum (%) Max. 0.10 Surface tension Max. 50 dynes/cm Particle size Mean Angstrom 1,400-2,500 Median Angstrom 1,400-2,500 Distribution Unimodal 95% range Angstrom Max. 2,000 Freeze-thaw stability (% coagulum after 2 cycles) Max. 0.10 Concrete slump Greater than standard Concrete air content Max. 9% Time for 50% slump loss ±25% standard Concrete compressive strength (24 hr and 28 days) Min. 75% standard Compressive strength loss (28-42 days) Max. 20% Concrete flexural strength (24 hr and 28 days) Greater than standard Flexural strength loss (28-42 days) Max. 25% Bond strength/slant shear (% monolithic latex concrete cylinder) Min. 45 Deicer scaling (50 cycles) Median grading Max. 3 Worst rated Below 5 Chloride permeability (95% absorbed) 1/16-1/2 in (% Cl-) Max. 0.320 1/2-1 in (% Cl-) Max. 0.064 Values for viscosity and density spectrographs of the solid portion and volatile portion shall be provided in the report.217.02 197Type I, Type II, Type III or Type K cement shall be used without mineral admixtures for latex- modified concrete.
c.Fine aggregate shall conform to Section 202 for Grading A.
d.Coarse aggregate shall conform to Section 203 for the class of concrete being produced.
e.Water shall conform to Section 216.
f.Admixtures shall conform to Section 215.
g.White Po rtland cement concrete shall conform to the requirements herein except as follows:
1.Cement shall be white portland cement conforming to Section 214 for Type I portland cement except that it shall contain not more than 0.55 percent by weight of Fe2O3.
2.Fine aggregate shall consist of clean, hard, durable, uncoated particles of quartz composed of at least 95 percent silica; shall be free from lumps of clay, soft or flaky material, loam, organic material, or other deleterious material; and shall conform to Section 202. It shall contain not more than 3 percent inorganic silt by actual dry weight when tested in accor - dance with AASHTO T11. Stone sands that produce an acceptable white concrete may also be used.
3.Coarse aggregate shall be crushed stone or crushed or uncrushed gravel conforming to Section 203.
h.Fly ash shall conform to Section 241.
i.Granulated iron blast-furnace slag shall conform to Section 215.
j.Concrete to which a high-range water reducer is to be added shall conform to Table II-17. Concrete shall be mixed 70 to 100 revolutions at mixing speed.
k.Silica fume shall conform to Section 215.
l.Concrete Repair Materials shall be from the Materials Division Approved List 31 and shall be in accordance with VTM 132.
217.03 Handling and Storing Materials
a.Aggregate shall be kept separated by size until batched. Aggregates shall be clean and shall be maintained in at least a saturated, surface-dry condition. Fine aggregate that has been washed shall not be used within 24 hours after being placed in the stockpile or until surplus water has disappeared and the material has a consistent free moisture content. Stockpiles shall be located and constructed so that surplus water will drain from stockpiles and the batcher.
b.Cement that is reclaimed or that shows evidence of hydration, such as lumps or cakes, shall not be used.217.03 198Loose cement shall be transported to the mixer either in tight compartments for each batch or between the fine and coarse aggregate. Cement in original shipping packages may be transported on top of the aggregates, with each batch containing the number of bags required.
c.Latex modifier shall be kept in enclosures that will protect it from exposure to temperatures below 40 degrees F or above 85 degrees F . Containers of latex modifier shall be protected from direct sunlight.
d.Admixtures shall be stored and handled so that contamination and deterioration will be prevented. Liquid admixtures shall be thoroughly agitated before use. Admixtures that are frozen or partially frozen shall not be used.
e.Aluminum forms, chutes, buckets, pump lines, and other conveying devices shall not be used if the aluminum comes in contact with concrete.
217.04 Measurement of Materials
Measuring devices shall be subject to the approval of the Engineer.
a.Stationary Production Plant:
1.Cement shall be measured by weight. Cement in standard packages of 94 pounds net per bag need not be weighed, but bulk cement and fractional packages shall be weighed within an accuracy of 1 percent.
2.Mixing water shall be measured by volume or weight. The water-measuring device shall be readily adjustable and capable of accurately delivering the required amount. The device shall have an accuracy of within 1 percent of the quantity of water required for the batch under all operating conditions.
3.Aggregates shall be measured by weight within an accuracy of 2 percent. Fine and coarse aggregate shall be weighed separately. Prior to mixing concrete, the moisture content of ag - gregates shall be determined and proper allowance made for the water content. The moisture content shall be determined prior to the start of mixing and thereafter as changes occur in the condition of aggregates. The Contractor shall perform moisture determinations and tests for slump and air content and provide necessary testing equipment.
4.Admixtures shall be dispensed and used according to the manufacturer’ s recommendations or instructions. Admixtures shall be added within a limit of accuracy of 3 percent by means of an approved, graduated, transparent, measuring device before they are introduced into the mixer. If more than one admixture is used, they shall be released in sequence rather than in the same instant. The sequence of dispensing admixtures shall not be altered once established. However, when the amount of admixture required to achieve the specified results deviates appreciably from the manufacturer’ s recommended dosage, use of the material shall be discon - tinued and the Engineer shall be notified of the change.
b.Mobile Production Plant: Aggregates, cement, and water shall be measured by weight or volume. If ingredients are measured by volume, the Contractor shall furnish, at his expense, approved scales and containers suitable for checking the calibration of the equipment’ s measuring system. The man - ufacturer’ s recommendations shall be followed in operating the equipment and calibrating the gages 217.03 199and gate openings. Mixing water shall be measured by a calibrated flow meter. The introduction of mixing water to the mixer shall be properly coordinated with the introduction of cement and ag - gregates. Ingredients shall be proportioned within the following tolerances, which are based on the volume/weight relationship established by calibration of the measuring devices: Ingredients Tolerance Cement 0 to +4% Fine aggregate ±2% Coarse aggregate ±2% Admixtures ±3% Water ±1% Tolerances will be applied to Department approved mixture design quantities. Means shall be provided whereby samples of the various ingredients can be taken from the feed prior to blending and mixing to test the calibration of the equipment.
217.05 Equipment
Equipment and tools necessary for handling materials and performing all parts of the work will be approved by the Engineer before use and must be in accordance with one of the following procedures:
1.having a current National Ready Mix Concrete Association Plant and Truck Certification, or
2.having a Department approved self-certification program in-place prior to the production of concrete for the Department. Failure to comply with one or the other of these procedures will result in the Department not approving the concrete and the work requiring concrete will not be allowed to proceed.
a.Batching Equipment: Bins with separate compartments for fine aggregate and for each required size of coarse aggregate shall be provided in the batching plant. Bins for bulk cement shall be arranged so that cement is weighed on a scale separate from those used for other materials and in a hopper free and independent of hoppers used for weighing aggregates. The weighing hopper shall be properly sealed and vented to preclude dusting during operation. Each compartment shall be designed to discharge aggregate efficiently and freely into the weighing hopper. A means of control shall be provided so that material may be added slowly and shut off with precision. A port or other opening shall be provided to remove any overrun of any of the several materials from the weighing hopper. Weighing hoppers shall be constructed to prevent accumulation of materials and to discharge fully. Scales used for weighing aggregates and cement shall be approved and sealed in accordance with Section 109.01. When beam scales are used, provision shall be made for indicating to the operator that the required load in the weighing hopper is being approached. The indicator shall indicate at least the last 200 pounds of load. Weighing and indicating devices shall be in full view of the operator while the hopper is charged, and the operator shall have convenient access to all controls.217.05 200(b) Mixers and Agitators: Mixers may be stationary or truck mixers. Agitators may be truck mixers or truck agitators. Each mixer and agitator shall have a metal plate(s) attached in a prominent place by the manufacturer on which the following are marked: the various uses for which the equipment is designed, capacity of the drum or container in terms of the volume of mixed concrete, and speed of rotation of the mixing drum or blades. Each stationary mixer shall be equipped with an approved timing device that will not permit the batch to be discharged until the specified mixing time has elapsed. Each truck mixer shall be equipped with an approved counter by which the number of revolutions of the drum or blades may be readily verified. The mixer shall be capable of combining ingredients of concrete into a thoroughly mixed and uniform mass and of discharging concrete with a satisfactory degree of uniformity. The agitator shall be capable of maintaining mixed concrete in a thoroughly mixed and uniform mass and of discharging concrete within a satisfactory degree of uniformity. Mechanical details of the mixer or agitator, such as the water measuring and discharge apparatus, condition of the blades, speed of rotation of the drum, general mechanical condition of the unit, and cleanliness of the drum, shall be checked by the Contractor and operator before use of the unit is permitted by the Engineer. Consistency tests of individual samples at approximately the beginning, midpoint, and end of the load shall be conducted upon request by the Engineer. If consistency measurements vary by more than 2 inches for slump between high and low values, the mixer or agitator shall not be used until the inconsistency is corrected.
c.Mobile Production Plants: The Contractor may produce Class A3 general use hydraulic cement concrete for incidental construction items from a mobile production plant. The Engineer will not allow the use of mobile production plants to produce concrete used in bridges, except overlays; box culverts; pavements, except patching; or retaining walls. If the Contractor elects to use a mobile production plant as permitted, the equipment requirements specified hereinbefore will not apply and the concrete shall be mixed at the point of delivery by a combination materials transport and mixer unit conforming to the following:
1.The unit shall be capable of carrying ingredients needed for concrete production in separate compartments and of mixing ingredients at the point of delivery. The unit shall be equipped with calibrated proportioning devices to vary mixture proportions of dry ingredients and water. The unit shall be capable of changing the slump at any interval of continuous discharge of concrete.
2.The mixing mechanism shall be a part of the transportation unit carrying dry ingredients. The mixer may be any type capable of combining ingredients for concrete production into a thoroughly mixed and uniform mass and of discharging concrete with a satisfactory degree of uniformity within the specified time of mixing.
3.Each unit shall have a metal plate(s) attached in a prominent place by the manufacturer on which the following are plainly marked: the gross volume of the transportation unit in terms of mixed concrete, discharge speed, and weight-calibrated constant of the machine in terms of an indicator revolution counter.
4.During discharge, the consistency, determined by the slump cone method (ASTM C143), of representative samples taken from the discharge of the mixer at random intervals shall not vary by more than 1 inch. 217.05 201(d) High Performance V olumetric Mixers (HPVMs): The Contractor may produce the specified class of hydraulic cement concrete in Table II-17 in accordance with Section 217.02(a) provided that the manufacturer’ s equipment meets the tolerance requirements of Section 217.04(a) and has a stamped plate from the V olumetric Mixers Manufacturers Bureau stating that the equipment con - forms to ASTM C685. This combination materials transport and mixer unit shall conform to the following:
1.The shall be equipped with calibrated proportioning devices for each ingredient added to the concrete mix. The unit shall be equipped with a working recording meter that is visible at all times and that furnishes a ticket printout with the calibrated measurement of the mix being produced. If the mixer fails to discharge a uniform mix at any time, production of concrete shall halt until any problems are corrected.
2.Each unit shall have a metal plate(s) attached in a prominent place by the manufacturer on which the following are plainly marked: the gross volume of the transportation unit in terms of mixed concrete, the discharge speed and the mass calibrated constant of the machine in terms of volume.
3.HPVMs shall be calibrated by a Department approved testing agency in accordance with the manufacturer’ s recommendations at an interval of every 6 months or a maximum production of 2500 cubic yards, whichever occurs first. The yield shall be maintained within a tolerance of ±1 percent and verified using a minimum 2 cubic feet container every 500 cubic yards or a minimum once per week.
4.The three cubic feet initially discharged from the truck shall be discarded and not used for concrete placement. Acceptance of the specified class of concrete shall comply with Section
217.08 except that the sample secured for acceptance testing will be taken after four cubic feet
is discharged from the delivery vehicle. During discharge, the consistency as determined by ASTM C143 on representative samples taken from the mixer discharge at random intervals shall not vary more than 1 inch. Acceptance tests shall be performed on each load. If test data demonstrates that consistent concrete properties are being achieved, the Engineer may reduce testing requirements.
5.The HPVM shall be operated by a person who is a certified operator by the HPVM manufac- turer. Any equipment adjustments made during the on-site production of concrete shall be done under the direct on-site supervision of the producer’ s VDOT Concrete Plant and Field Certified Technician. Each load of HPVM produced concrete shall be accompanied by a Form TL-28 signed by the producer’s VDOT Certified Concrete Plant Technician or a designated company representative working under the direct on-site supervision of the producer’s VDOT Certified Concrete Plant Technician. The form shall be delivered to the Inspector at the site of the work. Loads that do not carry such information or do not arrive in satisfactory condition shall not be used.
217.06 Classification of Concrete Mixtures
Classes and uses of concrete are specified in Table II-17.217.06 202217.06 Design Max . Max . Design Min . Design Max . Laboratory Water Laboratory Laboratory Permeability Nominal Min. /Cementitious Compressive Permeability at 28 Days - Max . Cementitious Mat. Air Strength at 28 Aggregate at 28 Days Over tidal water Aggregate Min. Grade Content (lb. Water Consistency Content Class of Concrete Days (f’c) (psi) Size No .6 (Coulombs)5 (Coulombs)5 Size (in) Aggregate (lb./cu yd) /lb. Cement) (in of slump) (percent)1 A5 Prestressed and 5,000 or as 57, 68, 1,500 1,500 1 A 635 0.40 0-4 4 1/2 ± 1 1/2 other special designs2 specified on 78, or 7 the plans A4 General 4,000 56 or 57 2,500 2,000 1 A 635 0.45 2-4 61/2 ± 1 1/2 Low Shrinkage 4,000 56 or 57 2,500 2,000 1 A N.A. 0.45 2-4 61/2 ± 1 1/2 A4 Mod. A4 Post & rails 4,000 7, 8 or 78 2,500 2,000 0.5 A 635 0.45 2-5 7 ± 2 A3 General 3,000 56 or 57 3,500 2,000 1 A 588 0.49 1-5 6 ± 2 A3a Paving 3,000 56 or 57 3,500 3,500 1 A 564 0.49 0-3 6 ± 2 A3b Paving 3,000 357 3,500 3,500 2 A N.A. 0.49 0-3 6 ± 2 B2 Massive or 2,200 57 N.A. N.A. 1 B 494 0.58 0-4 4 ± 2 lightly Reinforced C1 Massive 1,500 57 N.A. N.A. 1 B 423 0.71 0-3 4 ± 2 Unreinforced T3 Tremie seal 3,000 56 or 57 N.A. N.A. 1 A 635 0.49 3-6 4 ± 2 Latex hydraulic 3,500 7, 8 or 78 1,500 1,500 0.5 A 658 0.40 4-6 5 ± 2 cement concrete overlay3 Silica fume, 5,000 7, 8 or 78 1,500 1,500 0.5 A 658 0.40 4-7 6 ± 2 silica fume / Class F Fly Ash or silica fume / slag concrete overlay4 Class F Fly Ash 4,000 7, 8 or 78 1,500 1,500 0.5 A 658 0.40 4-7 6 ± 2 or slag overlayTABLE II-17 Requirements for Hydraulic Cement Concrete 203———————————————— (TABLE II-17 Notes) ———————————————— 1 When a high-range water reducer is used, the upper limit for entrained air may be increased by 1% and the slump shall not exceed 7 inches. The lower limit for entrained air remains unchanged. 2 When Class A5 concrete is used as the finishing bridge deck riding surface, or when it is to be covered with as phalt concrete with or without waterproofing, the air content shall be 5 1/2 ± 1 1/2 percent. Prestressed concrete structures over tidal water, beams and slabs within 15 feet of mean high tide and exposed piles shall contain a minimum 2.0 gallons per cubic yard of calcium nitrite with the calcium nitrite conforming to Section 215. 3 The latex modifier content shall be 3.5 gallons per bag of cement. Slump shall be measured approximately 4.5 min- utes after discharge from the mixer. 4 Silica fume with a minimum of 7% by weight of cementitious material; silica fume with a range of 2.5-5 % shall be combined with Class F Fly Ash in range of 15-20% and minimum cement of 77.5% by weight of cementitious mate - rial; silica fume with a range of 2.5-5% shall be combined with Ground Granulated Blast Furnace Slag in the range of 30-35% and a minimum cement of 67.5% by weight of cementitious material. 5 The permeability testing does not apply to concrete structures and incidental concrete as described in Sec tions 219, 232, 302, 415, 502, 504, 506 and 519. Curing and testing of test cylinders for permeability will be in accordance with VTM 112. 6 The Contractor may use different aggregate sizes or a combination of sizes to increase the coarse aggregate content of the concrete as approved by the Engineer. The maximum size of the coarse aggregate shall not exceed 2.5 inches. Note: The Contractor may substitute a higher class of concrete for that specified at the Contractor’ s expense with the approval of the Engineer. ——————————————————————————————————————————
217.07 Proportioning Concrete Mixtures
The Contractor is responsible for having a VDOT Certified Concrete Plant Technician available during batching operations, and a VDOT Certified Concrete Field Technician present during placing operations. A VDOT Certified Concrete Plant Technician is that person who is capable of performing adjustments to the proportioning of materials used to produce the specified concrete should adjustments become necessary. A VDOT Certified Concrete Field Technician is the person employed by the Contractor responsible for quality control of concrete work at the project site. The Contractor shall have at least one VDOT Certified Concrete Field Technician on the project for single or multiple incidental concrete placements. The Contractor shall have at least one VDOT Certified Concrete Field Technician present at each site during the placement of pavements, bridge decks, bridge piers and abutments, box culverts, and any placement of 50 or more cubic yards. The VDOT Certified Concrete Field Technician shall provide control over methods used for discharging, conveying, spreading, consolidating, screeding, finishing, texturing, curing, and protecting the concrete. Deficiencies in conformance to specification requirements and good concreting practices shall be correct - ed by or under the direction of the VDOT Certified Concrete Field Technician as soon as they begin to occur. The concrete producer shall plan batching operations so that delays do not occur because of the absence of certified personnel. Concrete shall be proportioned to secure the strength and durability required for the pavement or the part of the structure in which it is to be used.217.07 204The Contractor shall submit, or shall have his supplier submit, concrete mixture design(s) conforming to the specifications for the class of concrete specified for the Engineer’ s approval prior to the start of concrete mixing operations. The Contractor shall furnish and incorporate a Department approved water-reducing and retarding admixture in bridge deck concrete and in other concrete when conditions are such that the initial set may occur prior to completion of approved finishing operations. The Contractor shall supply and incorpo - rate only an approved water-reducing admixture in lieu of both the water-reducing and retarding admix - tures normally required in the bridge deck concrete to provide the required slump without exceeding the maximum water/cement ratio when the Engineer elects not to enforce the requirement for both admix - tures. The Contractor shall demonstrate to the Engineer that use of the admixture will not cause segre - gation. The two admixtures shall not be used together in the same concrete batch unless tests indicate the admixtures are compatible in accordance with Section 215.02(b). Costs for admixture(s) shall be included in the Contract unit price for the respective concrete item. Concrete shall be air entrained. The air content shall conform to Table II-17. Except for latex hydraulic cement concrete, concrete mixtures shall be developed and/or verified by any one of the following three options listed below. The mix design(s) as determined by the respective option below shall be valid provided there is no change in sources of aggregate, chemical admixtures, mineral admixtures, or hydraulic cement. All concrete mixtures shall contain the minimum amount of mineral admixtures or combination thereof expressed as a percent of the total cementitious materials in accordance with Section 217.02(a). All quantities of materials shall be weighed in accordance with tolerances specified in Section 217.04. The quantities of coarse and fine aggregates used in concrete production shall not deviate by more than ±5% by weight from the batch weights of the approved mix design. When low permeability concrete is specified, two 4 X 8 inch specimens shall be molded from concrete representing the proposed mix design and tested in accordance with VTM 112 to validate conformance. For trial batches, the tested permeability value shall be considered satisfactory provided it is 500 coulombs less than the specified maximum value for the class of concrete specified. Option 1 - Prescriptive Method: Mix proportions for normal, heavy weight, and lightweight concrete shall be established by the methods described in ACI 211, on an absolute volume basis, for the respective aggregate size and meeting all Table II-17 requirements for the class of concrete indicated. Aggregate properties ob - tained from the aggregate producer shall be used for design purposes. Once the proposed mix design has been established, the Contractor or their concrete supplier shall produce one 3-cubic yard production verification batch using the same type of equipment intend - ed for use in supplying concrete to the Department. The proposed mix design will be considered acceptable provided that the plastic properties of the concrete are within the Department’ s specifi - cation limits for the given class of concrete. Strength tests of the verification batch must equal or exceed f’c for the intended class of concrete. Option 2 - Trial Batch Mix Design Method: The minimum cementitious content requirement in Table II-17 shall be waived provided that the max - imum water-cementitious ratio requirement of Table II-17 is met for the respective class of concrete. 217.07 205The required grading for fine and coarse aggregate shall be waived provided the coarse aggregate meets the nominal maximum size as required in Table II-17 for the respective class of concrete. The Contractor or their concrete supplier shall prepare a minimum of 3 trial concrete batches with differing cementitious materials contents over a range anticipated to encompass the design strength, f ’c, plus overdesign, and water-cementitious ratios encompassing the range permitted for the classes of concrete being evaluated. Trial batches may be produced in either: Option 2A: Small scale laboratory batches, or Option 2B: Truck batches with a minimum batch volume of 3 cubic yards each. The plastic properties of the trial concrete batches shall meet the requirements for consistency and air content in Table II-17 and meet the additional requirements listed below: • The concrete temperature of the trial batches, as batched and sampled, shall be a minimum of 68 degrees F . • Air content of the trial batches shall within a range of -1.0 to + 1.5 percentage points of the median design air content for the classes of concrete being evaluated. • Slump of the trial batches shall be within ± 1 inch of the maximum slump permitted for the class of concrete. Three 4 X 8 inch test specimens shall be molded from each batch, cured in accordance with ASTM C 31 for acceptance specimens, and then compression tested at an age of 28 days. The strength re - sults of these tests shall be plotted on a graph to establish the relationship between the water-cemen - titious ratio and the compressive strength. Alternately, the relationship can be established between the cementitious content and the compressive strength. The design water-cementitious ratio, or de - sign cementitious content, can then be derived from the graph to satisfy the required design strength plus an appropriate overdesign to be designated as f ’cr. The required cementitious materials content determined from these tests can be interpolated from the established graph. If desired, the design water-cementitious ratio or cementitious content can be determined from a polynomial regression analysis of the plotted strength data. Test results from prior trial concrete batches are acceptable for use provided that they represent the same material sources proposed for the Department work, meet the requirements for trial concrete batches as stated above and are less than 18 months old. The required cementitious content to satisfy the strength requirement for the respective class of concrete shall be determined in accordance with either of the two following procedures:
1.When the concrete production facility has sufficient data to establish a production standard deviation(s), as described in Documentation of Previous Field Experience or Production Standard Deviation(s) . The cementitious content required to meet the design strength require - ment, f’cr, then the f’cr shall be based upon the following equation: f’cr = f’c + 3s
2.When the concrete production facility does not have a production standard deviation established the cementitious content required to meet the design strength requirement, f’cr, then the f’cr shall be based upon the following equation: f’cr = f’c + 1700 psi.217.07 206Once the proposed mix design has been established, the Contractor or their concrete supplier shall produce one 3-cubic yard production verification batch using the same type of equipment intend - ed for use in supplying concrete to the Department. The proposed mix design will be considered acceptable provided that the plastic properties of the concrete are within the Department’ s specifi - cation limits for the given class of concrete. Strength tests of the verification batch must equal or exceed f’c for the intended class of concrete. The requirement for a production verification batch shall be waived when the trial batching is performed by Option 2B -Truck batches. Option 3 - Documented Field Experience Method: The minimum cementitious content requirement in Table II-17 shall be waived provided that the maxi - mum water-cementitious ratio requirement of Table II-17 is met for the respective class of concrete. The required grading for fine and coarse aggregate shall be waived provided the coarse aggregate meets the nominal maximum size as required in Table II-17 for the respective class of concrete. An existing concrete mixture shall be considered acceptable for use provided that the Contractor or their concrete supplier has a satisfactory test record of pervious field experience as described in: Documentation of Previous Field Experience or Production Standard Deviation(s), and that the proposed concrete mixture meets the following requirements:
1.The water cementitious ratio of the proposed concrete mixture is less than or equal to the maximum water cementitious ratio specified for the respective class of concrete.
2.The documented average strength, f ’cr, equals or exceeds the design compressive strength f ’c for the respective class of concrete in accordance with the following equation: f’cr = f ’c + 3s.
3.proposed concrete mixture contains the same aggregate sources, supplementary cementitious materials type, and admixture type as those used to establish the previous field experience test record.
4.The consistency (slump) and air content are within the specification limits for the respective class of concrete. Documentation of Previous Field Experience or Production Standard Deviation(s) An acceptable test record to document previous field experience and/or to establish a production facility standard deviation shall represent a minimum of 30 consecutive compressive strength tests results, encompass a production period of at least 45 days and test data not more than 18 months old. A test record of less than 30 tests, but not less than 15 tests, shall be permitted provided a modification factor is applied to the production facility sample standard deviation as shown below: Multiply Standard Deviation by Modification Factor Number of Test Modification Factor 15 1.16 20 1.08 25 1.03 30 1.00217.07 207The test record does not necessarily have to be based on Department projects provided that documentation of the source(s) of concrete strength test results accompanies the submittal. For latex hydraulic cement content, the dry weight ratio of cement/fine aggregate/coarse aggregate shall be 1:2.5:2. With the Engineer’ s approval a maximum adjustment of 10 percent may be made in aggregate weights to compensate for grading changes and variable specific gravity. The Contractor shall adjust batch quantities during the course of the work to compensate for changes in workability caused by differences in the characteristics of aggregates and cements permitted within the specification requirements. Such adjustments shall be made only by the Contractor and shall not change the yield. If concrete cannot be obtained with the required workability or consistency or within the maximum design water content with the materials furnished, the Contractor shall make changes to secure the desired properties subject to the limiting requirements specified in Table II-17 and the Engineer’ s approval. The Contractor shall use a fine aggregate having a void content of less than 50.5 percent when the void content of the fine aggregate is more than 50.5 percent and the concrete does not have the desired properties. In lieu of changing the fine aggregate, the Contractor may take one or more of the following actions:
a.Use a Department approved water-reducing admixture.
b.Increase the cement content.
c.Change the source of coarse aggregate.
d.In hot weather, add ice or otherwise reduce the temperature to increase the workability.
e.Submit other recommendations to the Engineer for approval. The Contractor shall make trial batches under the observation of the Engineer to verify that concrete of the required workability and consistency is obtained within the specified water content when any of the actions is exercised. At least one trial batch shall be made with the concrete temperature at approximately 90 degrees F to verify that the concrete mixture has sufficient workability and consistency without ex - ceeding the specified water content. The concrete mixture shall be redesigned when the fineness modulus of the fine aggregate changes more than 0.2 from the original design and the concrete does not have the desired properties. Costs incurred because of adjustments of concrete mixture design(s) and for trial batches shall be borne by the Contractor with no additional compensation being made.
217.08 Acceptance
a.Air Consistency Tests: Air and consistency tests will be performed by the Department prior to discharge of concrete into the forms to ensure that specification requirements are consistently being complied with for each class of concrete supplied. The sample secured for the tests shall be taken after at least two cubic feet of concrete has been discharged from the delivery vehicle. The two cubic feet discharged is not to be used as part of the test sample. The Engineer must authorize any devi - ation from sampling and testing procedures. The Contractor shall provide a receptacle conforming to ASTM C31 for the Department’ s use in obtaining the sample. If either determination yields a result that is outside of the allowable range for air content or consistency, the Engineer will use the following procedure:
1.The Engineer will immediately perform a recheck determination. If the results confirm the original test results, the load will be rejected.217.08 208 2. The Contractor’ s representative will be immediately informed of the test results.
3.The Contractor’ s representative shall notify the concrete producer of the test results through a pre-established means of communication. The Engineer may perform any additional tests deemed necessary and reject all remaining material that fails the tests. Entrained air content will be determined in accordance with ASTM C231 or ASTM C173. Accep - tance or rejection will be based on the results obtained from these tests. In general, a mixture that contains the minimum amount of water consistent with the required workability shall be used. Consistency will be determined in accordance with ASTM C143. The Engineer will not allow adding cement to loads previously rejected for excessive water content or unsatisfactory consistency.
b.Strength Tests: The 28-day compressive strengths (f ’c) specified in Table II-17 are the strengths used in the design calculations. The Engineer will verify design strengths by tests made during the progress of the work in accordance with ASTM C31 (Standard Practice for Making and Curing Concrete Test Specimens in the Field) and ASTM C39 (Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens) except that the fresh concrete sample used for testing is to be secured after at least two cubic feet has been discharged from the delivery vehicle. The two cubic feet discharged is not to be used as part of the test sample or in the work. The Engineer must pre authorize any deviation from sampling and testing procedures. The use of ASTM C42 (Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete) will be at the Engineer’ s discretion. If the 28-day design compressive strength (f ’c) test results do not conform to the strength requirements specified in Table II-17, the Contractor shall take immediate steps to adjust the mixture design. In addition, the Engineer may require removal of or corrective measures be applied to any concrete that does not meet the requirements of Table II-17. If the concrete cylin - der strength, f’cyl, is less than the specified compressive strength found in Table II-17, the criteria in Table II-17A shall apply: TABLE II-17A Price Reduction or Action Taken due to f’ cyl not meeting the specification value f’ c listed in Table II-17 Condition Concrete is a Pay Item Concrete is Not a Pay Item f’cyl is greater than or equal to 98% f’ c A A f’cyl is greater than or equal to 90% f’ c B C and less than 98% f’ c f’cyl is less than 90% f’ c D D f’cyl is not available due to the Contractor’ s D D inappropriate handling and storage of specimens in accordance with ASTM C31 f’c is the 28-day design compressive strength requirement found in Table II-17. f’cyl is the actual average tested strength of the standard-cured concrete cylinder made and tested in accordance with ASTM C31 and ASTM C39. A = full payment B = pay reduction = [((f’ c - f’ cyl)/f’ c) x Contract unit price for concrete per yd3 x number of yds3 the concrete represents] or $500, whichever is greater.217.08 209 C = pay reduction = [((f’ c - f’ cyl)/f’ c) x 5 x Contractor’ s invoice price for concrete per yd3 x number of yds3 the concrete represents] or $500, whichever is greater. D = The Contractor shall submit an investigative plan stamped by a Professional Engineer holding a valid license to practice engineering in the Commonwealth of Virginia outlining how the Contrac - tor shall demonstrate that the in-place concrete meets the structural strength requirements for the de - sign. The Engineer will not permit any reduction in concrete strength below 0.9f’c for barriers, par - apets, railings, etc. The Engineer will approve the investigative plan for all other applications prior to the execution of the investigation. All costs associated with this investigation shall be borne by the Contractor. After the investigation is completed, the Contractor shall submit a report to the Engineer showing the results of the Professional Engineer’ s analysis, testing and conclusions as well as any recommended actions proposed by the Contractor to be taken with the concrete that did not meet the strength requirements. The Department retains all rights to determine if the action proposed with regard to the concrete in question is acceptable. If the Department concurs with the proposed action and the concrete meets the structural strength requirements of the design and remains in place, any price reduction will be taken by Method B if the concrete is a pay item or Method C if the concrete is not a pay item. If the concrete does not meet the structural requirements of the design, the concrete shall be removed and replaced at no cost to the Department. The maximum penalty assessed for low strength concrete left in place will be 10% as specified in Table II-17A, not including the cost of the investigation and any corrective measures taken by the Contractor. The Department will not assess a calculated penalty less than $500. The Contractor shall have the right to remove and replace concrete failing to meet specifications at the Contractor’ s cost. Before concrete is placed, the Contractor shall provide a storage chamber at his expense for tempo - rary storage of the Department’ s concrete cylinders. The Contractor shall be responsible for main - taining the chamber so that the concrete test cylinders are kept in a continuously moist condition and within a temperature range of 60 degrees F to 80 degrees F . The chamber shall be equipped with a continuously recording thermometer accurate to ± 2 degrees F for the duration of concrete cylinder curing. The Contractor shall provide the data from the continuously recording thermometer within time frames as approved by the Engineer. The chamber shall be located in an area where the test cylinders will not be subject to vibration and shall be of sufficient size or number to store, without crowding or wedging, the required number of test cylinders as determined by the Contractor based on his plan of operations. The Engineer will approve the location of the chamber prior to its placement. When use of high-early-strength hydraulic cement concrete is required, it shall conform to Table II–17 except that the 28-day compressive strength requirement shall be obtained in 7 days. The Contractor may use up to 800 pounds per cubic yard of Type I, Type II or Type III cement to produce high-early-strength concrete.
c.Concrete Temperature shall be measured in accordance with ASTM C1064.
d.Quality Assurance for Low Permeability Concrete: General The Contractor shall prepare and cast test specimens on at least two trial batches using job materials, with permissible combination of cementitious materials, for testing by the Department for permeability and strength at least 5 weeks before the field application. The permeability samples shall be cylindrical specimens with a 4-inch diameter and at least 4-inches in length. Cylinders will be tested at 28 days in 217.08 210accordance with VTM 112. The test value shall be the result of the average values of tests on two speci - mens from each batch. Permeability values obtained from trial batches shall be 500 coulombs below the maximum values specified in Table II-17 to be acceptable. Acceptance Tests For each set of cylinders made for compressive strength tests, two additional cylinders shall be made for the permeability test. The Department will be responsible for making and testing all permeability test specimens. If the average permeability test result is equal to or less than the value for the specified class of concrete in Table II-17, then full payment will be made for the lot the average permeability test result represents. However, if the average permeability test result exceeds the coulomb value in Table II-17, the percent reduction in payment for that lot of concrete shall be calculated by multiplying 0.005 by each coulomb above the coulomb value in Table II-17 by the concrete item Contract unit price times the number of cubic yards or cubic meters of concrete in the lot. The reduction in price will not exceed 5 percent of the concrete item Contract unit price. The Engineer will reject any concrete with a coulomb value that exceeds the maximum required in Table II-17 by 1000 coulombs. However, bridge deck concrete with any coulomb value exceed - ing the maximum required value by over 1000 coulomb may be accepted by the Engineer at 95 percent of the Contract unit price if the concrete in question has the required strength, meets the other specification requirements and the Contractor applies, at his own expense, an approved epoxy concrete overlay to the top of the entire deck. In such cases deck grooving will not be required. The Engineer will not allow the placement of epoxy overlays over latex overlays. The Contractor shall make the adjustment to the roadway grade as required by the Engineer at the Contractor’ s expense. Similarly, concrete in abutments and pier caps with coulomb value exceeding the maximum required in Table II-17, by more than 1000 coulomb may be accepted at 95 percent of the Contract unit price if it has the required strength, meets the other specification requirements and the Contractor applies, at his own expense, one coat of epoxy Type EP 3B and one coat of epoxy EP 3T in conformance with Section 243.02, on top of the pier caps or abutment seats.
e.Bond Strength for Silica fume concrete, latex-modified concrete and very-early-strength latex- modified concrete overlays: Bond Strength, minimum at 7 days, VTM 92: 150 psi or failure in the substrate concrete at a depth > 0.5-in over > 50 percent of the test area. The Contractor shall perform the bond strength testing. Tests shall be performed one or more days after the overlay is placed and at a time when the lane can be closed to traffic with a minimum of inconvenience to the public. A minimum of one test result (based upon the average of three test specimen results) shall be conducted on each placement.
217.09 Mixing
The Engineer must approve the Contractor’ s method of mixing prior to the start of concrete work. The volume of concrete mixed per batch shall be at least 15 but not more than 110 percent of the mixer’ s rated capacity. Concrete that becomes nonplastic, unworkable, or outside the limits of the slump specified shall not be used. Retempered concrete shall not be used. The Contractor shall regulate concrete delivery so that 217.08 211placement is at a continuous rate. Intervals between deliveries of batches shall not be so great as to allow concrete in place to begin its initial set.
a.Mixing at Job Site: Concrete shall be mixed in a batch mixer designed to ensure a uniform distribution of materials throughout the mass. When bag cement is used, batches shall be propor - tioned on the basis of integral bags of cement. Mixing shall be performed in accordance with the requirements herein. The mixer shall be thoroughly cleaned upon cessation of mixing for more than 30 minutes.
b.Ready-Mixed Concrete: Ready-mixed concrete shall be delivered to the designated point ready for use. Each load of transit or shrink-mixed concrete shall be accompanied by Form TL-28 signed by the VDOT Certified Concrete Plant Technician or a designated company representative working under the direction of the VDOT Certified Concrete Plant Technician. The form shall be delivered to the Inspector at the site of the work. Additional TL-28’ s shall be delivered as needed on the project such as when additional space is needed on the form or there is a change in mix design. The Engineer will reject loads that do not carry such information or that do not arrive in satisfactory condition. The mixer shall be thoroughly cleaned upon cessation of mixing for more than 30 minutes. Each batch of concrete shall be delivered to the site of work and discharged within 90 minutes of the time the cement is introduced into the mixture unless the Engineer approves otherwise. Mixing and delivery shall be in accordance with the following:
1.Transit mixing: Concrete shall be mixed in a truck mixer. Mixing shall begin immediately after all ingredients are in the mixer and shall continue for at least 70 revolutions of the drum or blades at the rate of at least 14 but no more than 20 revolutions per minute. Additional rotations of the drum or blades shall be at the rated agitating speed. The mixer shall be operated within the capacity and speed of rotation designed by the manufacturer.
2.Shrink mixing: Materials, including water, shall be partially mixed in a stationary mixer for at least 30 seconds. Mixing shall be completed in a truck mixer with at least 60 but not more than 100 revolutions of the drum or blades at the rated mixing speed. Additional rotations of the drum or blades shall be at the rated agitating speed. Mixers shall be operated within the capacity and speed of rotation designated by the manufacturer of the equipment.
3.Central mixing: Concrete shall be completely mixed in a stationary mixer and transported in agitator equipment to the point of delivery. The Engineer will approve the use of nonagitator equipment only when the plant is in the immediate vicinity of the project. Mixing time for mixers having a capacity of 1 cubic yard or less shall be at least 60 seconds. Mixing time for mixers having a capacity of more than 1 but less than 10 cubic yards shall be at least 75 seconds. Mixing times for mixers having a capacity of more than 10 cubic yards shall be as determined by the Engineer. Performance tests to verify mixing time shall be con - ducted in accordance with VTM-17 by an approved commercial laboratory at the Contractor’ s 217.09 212expense. The Engineer will only approve shorter mixing times if the producer of the concrete is in conformance with VTM-17. In any event, mixing time shall be not less than 40 seconds. VTM-17 shall not be construed as a nullification of the requirements of Table II-17. If sub - sequent evaluation check tests indicate that the reduced mixing time is not satisfactory, the Contractor shall reestablish the necessary mixing time. The Engineer will reject concrete mixed for less than the specified time. Mixing time starts when solid materials are in the mixing compartment and ends when any part of the concrete begins to discharge. The mixer shall be operated at the drum speed specified on the nameplate of the approved mixer. Bodies of nonagitating equipment used to transport concrete shall be smooth, mortar tight, non-aluminum metal containers capable of discharging concrete at a controlled rate without segregation. Upon discharge of concrete, the body of the equipment shall be free from con - crete. Concrete shall be delivered to the work site in a thoroughly mixed and uniform mass. Upon the request of the Engineer, consistency tests of individual samples at approximately the beginning, midpoint, and end of a load shall be conducted. If consistency measurements vary by more than 2 inches for slump between high and low values, mixer or agitator equipment shall be used in lieu of nonagitating equipment.
c.Automatic Mobile Continuous Mixers: Mobile continuous mixers shall be calibrated to proportion the mixture accurately and shall have been certified prior to their use on the project for the type of material specified. Certifications will be valid for 6 months or until the source of materials changes or the grading or moisture changes significantly so as to affect the consistency of the concrete mix - ture. Evaluation and certification of the mixer will be performed by the Department or an approved testing agency to verify that the true yield is within a tolerance of ±1.0 percent. A recording meter, visible at all times and equipped with a ticket printout, shall indicate the calibrated measurement.
d.Hand Mixing: Hand mixing will be permitted only in case of emergency and with the Engineer’ s permission. Batches shall be not more than 1/2 cubic yard and shall be mixed in a watertight container in a manner approved by the Engineer. Ingredients shall be measured by placing them in any suitable, rigid container in the volumetric proportions of 1 part cement to 2 parts fine aggregate to 2 1/2 parts coarse aggregate. The container shall be filled and leveled with each ingredient to ensure the proportions specified are as near to their prescribed amounts as possible. Water shall then be added to produce a mixture having a slump of not more than 3 inches.
217.10 Placement Limitations
The Contractor shall be responsible for the quality of concrete placed in any weather or atmospheric condition. At the time of placement, concrete shall have a temperature in accordance with the following:
a.Class A3 general use concrete used in the construction of incidental items specified in Division V , except retaining walls, shall have a temperature of at least 40 degrees F but not more than 95 degrees F .
b.Class A3 paving concrete placed by the slipform method and containing an approved water reducer shall have a temperature of at least 40 degrees F but not more than 95 degrees F .
c.Concrete used in the construction of bridge decks shall have a temperature of at least 40 degrees F but not more than 85 degrees F .217.09 213(d) Retaining walls and other concrete not specified in (a), (b), or (c) herein shall have a temperature of at least 40 degrees F but not more than 90 degrees F . In cold weather, water and aggregates may be heated to not more than 150 degrees F to maintain concrete at the required temperature. The heating apparatus shall be such that materials will be heated uniformly and the possibility of the occurrence of overheated areas that might damage materials will be precluded. Steam shall not come in contact with aggregates. Cement shall not be heated. Heating equipment or methods that alter or prevent entrainment of the required amount of air in concrete shall not be used. Materials containing frost, lumps, crusts, or hardened material shall not be used to produce concrete. In hot weather, aggregates or the mixing water shall be cooled as necessary to maintain the temperature of the concrete within the specified maximum temperature.
217.11 Self Consolidating Concrete (SCC)
When specified or designated on the plans, SCC shall be designed as the Class of Concrete specified in Table II-17 and conform to all the requirements herein except as outlined below. Combined aggregate grading and viscosity modifying admixture (VMA) may be used. The viscosity-modifying admixture shall conform to ASTM C494, Type S. Synthetic fibers from the Materials Division Approved Products List 35 may be added to control cracking. Shrinkage-reducing admixture may be added to control shrinkage with the approval of the Engineer. The maximum size of aggregate shall be 3/4-inch. Further, the maximum size shall, not be larger than 1/5 the narrowest dimension between the sides of the forms, not be larger than 1/3 the slab depth and not be larger than 3/4 of the minimum clear spacing be - tween individual reinforcing bars or wires, bundles of bars, individual tendons, bundled tendons or ducts. The Contractor shall furnish the Engineer a mix design for the SCC to be used in accordance with the following: Proportion the mixture according to the project specific criteria for compressive strength, air content, slump flow, VSI, J-Ring value, and segregation factor. The maximum water-cementitious materials ratio shall be 0.45 unless otherwise approved by the Engineer. Use the same components in the trial batches as are to be used in the project including coarse and fine aggregates, water, source and type of cement, supplementary cementitious materials, and admixtures; including any site-added admixtures intended to be used. Laboratory and field testing of SCC shall conform to the following:
a.Slump Flow shall be measured in accordance with ASTM C1611, Procedure B. The slump flow shall be 26 ±3 inches, and there shall be no visible segregation of the mix in the spread. The slump flow shall be compared to the slump flow with the J-ring in accordance with ASTM C1621.
b.Visual Stability Index (VSI): VSI Rating in accordance with ASTM C 1611 shall not exceed 1.
c.J-Ring Flow: The difference between slump flow and J-Ring flow as measured by ASTM C 1621 shall not be more than 2 inches.217.11 214(d) Stability (performed on trial batches): The stability of the concrete shall be determined in the laboratory prior to approval of the SCC mix - ture using test method ASTM C 1610. Concrete mixtures shall have a maximum static segregation (segregation factor) of 15 percent.
e.Strength and Permeability Test Specimens: Test specimens for strength and permeability (if specified) shall be sampled in accordance with
217.12 Low Shrinkage Class A4 Modified Concrete
Low shrinkage Class A4 modified concrete shall conform to either of the following:
a.The cementitious materials content shall be < 600 pounds per cubic yard. High-early- strength hydraulic cement concrete as described in Section 217.08 (b) shall not be used. The 28 day drying shrinkage shall be < 0.035% (based on average of three specimens) when tested in accordance with ASTM C 157. Specimens shall be moist cured for 7 days prior to testing for drying shrinkage. A shrinkage reducing admixture shall be used unless the 28 day drying shrinkage is < 0.035% without the admixture. With appropriate documentation, a fixed amount of SRA dosage can be used without additional drying shrinkage testing if approved by the Engineer. The Contractor, at the Contractor’ s expense, shall prepare a minimum 3 cubic yard trial batch of the mix at least 5 weeks prior to the proposed start date of production. The trial batch will be used to verify compliance with the shrinkage requirements listed herein and the minimum compressive strength, permeability, air void content, and slump listed in Table II-17. The Contractor shall prepare the trial batch with the same equipment to be used on the project. The Contractor shall obtain the services of a Department approved independent laboratory to perform the trial batch testing. Test results shall be furnished to the Engineer for review and approval. The Engineer will not authorize the Contractor to proceed with production of low shrinkage Class A4 modified concrete for the work required by the Contract until the test results verify conformance with the requirements stated herein.
b.Use lightweight concrete with lightweight aggregates in conformance with AASHTO M195 (ASTM C330). The maximum cementitious materials content shall be 650 pounds per cubic yard. All other requirements shall conform to those listed in Table II-17 for Low Shrinkage Class A4 Modified concrete. Maximum density of freshly mixed lightweight concrete, when tested according to ASTM C138, shall be 120 lbs./cu.yd., or as specified on the plans.
217.13 Latex-modified Concrete, V ery-Early-Strength (LMCVE), for Bridge Deck Overlays
LMCVE shall conform to the requirements herein, except as follows:217.11 215Cement shall be approximately 1/3 calcium sulfoaluminate (C4A3S) and 2/3 dicalcium silicate (C2S) or other hydraulic cement that will provide a Latex-Modified Concrete that meets the physical requirements indicated in this section. The LMCVE shall contain a minimum 658 lbs per cubic yard of rapid hardening cement, 15% styrene butadiene latex by weight of cement, water not to exceed a water-cement ratio of 0.40, and aggregates as proposed by the Contractor for the mixture. The compressive strength minimum shall be 2500 psi at 3 hours and 3500 psi at 24 hours. Compressive strength specimens shall be cured in the molds in the same environment as the in-place LMCVE tested. Specimens shall remain undisturbed at the site for 2 hours and shall be transported to the testing lab for testing. Prior to placing overlay the Contractor shall calibrate the mobile concrete mixers. Once the mixers are calibrated, the mixtures shall be sampled and tested for slump and air content. The Contractor shall prepare and test specimens to demonstrate that the concrete mixture shall obtain a compressive strength of at least 2500 psi within 3 hours at the curing temperatures in which the overlay will be placed, and a compressive strength of at least 3500 psi at an age of 24 hours. All trial batching and prepatory work prior to placing LMCVE shall be at the Contractor’ s expense. During the placement of the overlay the Contractor shall take samples for testing for compressive strength. Permeability, slump and air content measurements will not be required, but may be performed by the Engineer.
217.14 High Early Strength Latex Modified Concrete (HESLMC) for Bridge Deck Overlays
High Early Strength Latex Modified Concrete (HESLMC) shall conform to the requirements herein and Table II-17, Latex hydraulic cement concrete overlay, except as follows: The compressive strength minimum shall be 3500 psi in 7 days. Prior to placing overlay the Contractor shall calibrate the mobile concrete mixers. Once the mixers are calibrated, the mixtures shall be sampled and tested for slump and air content. The Contractor shall prepare and test specimens to demonstrate that the concrete mixture will obtain a compressive strength of at least 3500 psi at an age of 7 days. All trial batching and preparatory work prior to placing HESLMC shall be at the Contractor’ s expense. Permeability, slump and air content measurements will not be required, but may be performed by the Engineer. SECTION 218—HYDRAULIC CEMENT MORTAR AND GROUT
218.01 Description
These specifications cover hydraulic cement mortar and grout used in bonding units together, filling voids, and making surface repairs.
218.02 Materials
a.Hydraulic cement shall conform to Section 214.
b.Fine aggregate shall conform to Section 202.218.02
Source: Virginia Road and Bridge Specifications, 2020 Edition. Pages 223–242 of 1,065.