atch 1 2515 Concrete Pavements.pdf

Concrete Pavements for Airfields FA5000-12-R-0001 Attachment 1

2515- 1

1. APPLICABLE PUBLICATIONS:

The publications listed below form a part of this specification to the extent referenced. The publications are referred to in the text by basic designation only.

1.1 ACI (American Concrete Institute)

: 306R Cold Weather Concreting 308 Curing Concrete.

1.2 American Society for Testing and Materials (ASTM)

: C 31 Making & Curing Concrete Test Specimens in the Field C 33 Concrete Aggregates C 39 Compressive Strength Cylindrical Concrete Specimens C 78 Flexure Strength of Concrete C 94 Ready Mixed Concrete C 123 Lightweight Pieces in Aggregate C 136 Sieve Analysis of Fine and Coarse Aggregates C 142 Clay Lumps and Friable Particles in Aggregates C 143 Slump of Portland Cement Concrete C 150 Portland Cement C 171 Sheet Materials for Curing Concrete C 172 Sampling Freshly Mixed Concrete C 173 Air Content of Concrete by the Volumetric Method C 174 Measuring Length of Drilled Concrete Cores C 231 Air Content of Concrete by the Pressure Method.

2. MATERIAL ACCEPTANCE TESTING:

2.1 Preconstruction Sampling and Testing:

2.1.1 Approval of Aggregates: The source of material to be used for producing aggregates shall be selected well in advance of the time aggregates will be required in the work. When required, tentative approval of the source will be based on an inspection by the Contracting Officer or his/her designated representative. Tentative approval of the material will be based on results of samples of current production in case of an existing producer. The tests to which the aggregates will be subjected may include specific gravity, absorption, Los Angeles abrasion, soundness in magnesium sulfate, petrography analysis, freezing and thawing in concrete, alkali or carbonate-aggregate reaction, organic impurities and any other tests necessary to demonstrate that concrete of acceptable quality and cost can be produced from the materials proposed.

2.2 Acceptance Sampling and Testing During Construction:

2.2.1 Aggregates: During construction, aggregates will be sampled for acceptance testing before delivery to the mixer to determine compliance with specification provisions. The Contractor shall provide facilities and labor as may be necessary for the ready procurement of representative samples. Samples as delivered to the mixer shall be obtained when directed by the Contracting Officer or his/her designated representative and under his supervision. The Contractor will test such samples. Required tests of aggregates at various stages in the process and handling operations will be made by the Contracting Officer or his/her designated representative.

2.2.2 Cement: Cement shall be sampled at the mill and the site of the work and tested by the Contractor. If tests prove that cement that has been delivered is unsatisfactory, it shall be promptly

Pavements - IDIQ

FXSB 11-2102

Section 2515

Concrete Pavements for Airfields

2515- 2 removed from the site of the work. Cement that has not been used within six months after testing will be retested at the expense of the Contractor when directed by the Contracting Officer or his/her designated representative and shall be retested if test results are not satisfactory.

2.2.2.1 Other Cement Sources: The sampling, testing and shipping inspection from the point of sampling when the point of sampling is other than at the site of the work will be done by the Contractor under the supervision of the Contracting Officer or his/her designated representative.

Cement meeting all other requirements may be accepted before the required seven-day age when the strength is equal to or greater than the seven day requirement. In the event of failure, the cement may be re-sampled and tested at the request of the Government and at the Contractor's expense. When the point of sampling is other than at the site of the work, the fill gate or gates of the sampled bin will be sealed and kept sealed until shipment from the bin has been completed. Sealing of the fill gate or gates and of conveyances used in shipment will be done by or under the supervision of the Government. Conveyances will not be accepted at the site of the work unless received with all seals intact. If tested cement is re-handled at transfer points, the extra cost of inspection will be at the Contractor's expense.

2.2.3 Pozzolan: Pozzolan will be sampled at the source and stored in sealed bins pending completion of certain tests. When determined necessary, pozzolan will also be sampled at the site.

All sampling and testing will be performed by and at the expense of the Contractor. Release for shipment and approval for use will be based on compliance with seven-day lime-pozzolan strength requirements and other physical, chemical and uniformity requirements for which tests can be completed, as well as on continuing compliance with the other requirements of the specifications. If the sample from a bin fails, the contents of the bin may be sampled as it is loaded into cars or trucks, provided they are kept at the source until released for shipment. Unsealing and resealing of bins and sealing of shipping conveyances will be done by or under the supervision of the Government. Shipping conveyances will not be accepted at the site of the work unless they are received with all seals intact. If pozzolan is damaged in shipment, handling or storage, it shall be promptly removed from the site of the work. Pozzolan not used within six months after testing will be retested at the expense of the Contractor when directed by the Contracting Officer or his/her designated representative and shall be rejected if the test results are not satisfactory. If tested pozzolan is re-handled at transfer points, the extra cost of inspection will be at the Contractor's expense.

2.2.4 Admixtures: The Contractor shall provide satisfactory facilities for ready procurement of adequate test samples. All sampling and testing of an admixture will be by and at the expense of the Contractor. Tests will be conducted with materials proposed for the project. An air-entraining admixture that has been in storage at the project site for longer than six months or that has been subjected to freezing will be retested at the expense of the Contractor when directed by the Contracting Officer or his/her designated representative and shall be rejected if test results are not satisfactory.

2.2.5 Curing Compound: The Contractor shall provide satisfactory facilities for ready procurement of adequate test samples. The sampling and testing will be by and at the expense of the Contractor.

2.2.6 Epoxy-Resin Material: When this material is required to be used for repairing new concrete, the Contractor shall submit certified copies of test results showing that the specific lots or batches from which the material will be furnished to this project have been tested by the manufacturer and that the material conforms to the requirements of these specifications.

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3. MIXTURE PROPORTIONING FOR NORMAL CONCRETE MIX DESIGN:

3.1 Composition: Concrete shall be composed of cementitious material, water, fine and coarse aggregates and admixtures. The cementitious materials shall be Portland Cement. The admixture shall be an air-entraining admixture.

3.2 Control: The proportions of all material entering into the concrete will be furnished by the Contractor. The proportions will be changed as necessary to maintain the workability, strength and standard of quality required for the concrete covered by these specifications, and to meet the varying conditions encountered during the construction. The Contracting Officer or designated representative shall be notified before any changes are made to the proportions of materials.

3.3 Cement Content: The cement content of the concrete will be that necessary to meet the strength requirements specified with a minimum of 6.25 sacks/CY

. When a pozzolan is used, the absolute volume of cementitious material will be the same as required for cement but shall not exceed 25 percent of the solid volume of Portland Cement plus pozzolan.

3.4 Aggregate Gradation

: The amount of coarse and fine type aggregate used in the concrete mixture shall be as determined by the mixture proportioning studies. The concrete aggregate gradation range for each sieve size shall be provided for approval to the Contracting Officer.

3.5 Flexural Strength: Proportioning requirements for normal concrete shall be designed for a minimum flexural strength of 650 psi at 28 days when tested in accordance with ASTM C 78. At the option of the Contracting Officer, 650 psi at 7 days concrete may be required.

3.6 Air Content: The air content by volume based on measurements made immediately after discharge from the mixer shall be between 4.5% and 6.5% determined IAW ASTM C 23l.

3.7 Slump: Concrete slump shall be between 2 and 3 inches

determined IAW ASTM C l43.

3.8 Portland Cement: Portland cement shall conform to ASTM C 150, Type I/II

3.9 Fly Ash: Ensure fly ash conforms to ASTM C 618, Class F, including the optional requirements for drying shrinkage, uniformity, and effectiveness in controlling Alkali-Silica reaction and has a loss on ignition not exceeding 3 percent. Ensure class F fly ash has a Calcium Oxide (CaO) content of less than 8 percent. Proportioning requirements for concrete shall be designed for a minimum flexural strength of 650 psi at 56 days when tested in accordance with ASTM C 78.

3.10 Concrete Mix Design

: Prior to placement of concrete, the Contractor shall submit for approval a concrete mix design for each of the types of concrete specified that will produce concrete of the properties specified.

3.10.1 The mix design shall include: the dry weight of cement; saturated surface-dry weights of fine and coarse aggregates; quantity of water per cubic yard of concrete; quantity, type, and name of all admixtures; gradation of the concrete aggregates; flexural strength, slump, air content, & water/cement ratio of previously performed test results for submitted mix design.

3.10.2 The mix design shall be based on the 28 day flexural strength breaks, unless indicated otherwise on the delivery order. Full payment will be based on 28 day flexural strength breaks, unless verified otherwise by the project manager based on the 7 day or 56 day flexural strength

2515- 4 breaks. 50% partial payment is recommended with acceptable 7 day flexural strength breaks.

4. NO LONGER USED

5. APPROVAL OF PLANT, EQUIPMENT AND CONSTRUCTION METHODS:

5.1 Plant and Equipment:

5.1.1 Batch Plant: Details and data on the concrete plant shall be submitted for approval.

5.1.2 Mixers: The make, type, capacity and number of the concrete mixers proposed for use shall be submitted for approval.

5.2 Construction Methods:

5.2.1 Hauling Equipment: A description of the equipment proposed for transporting concrete from the central mixing plant to the placing equipment shall be submitted for approval.

5.2.2 Placing Equipment: A description of the equipment proposed for placing concrete and the method of placing shall be submitted for approval.

5.2.3 Finishing Equipment: A description of the equipment proposed for surface texturing and the method of surface texturing shall be submitted for approval.

5.2.4 Curing: The curing media and methods to be used shall be submitted in writing for approval.

The Contractor shall notify the Contracting Officer or his/her designated representative of the source from which the curing compound is to be obtained at least 15 days in advance of the time concrete placing is expected to begin. A manufacturer's certificate shall be furnished by the Contractor certifying that the impervious sheet curing materials, if used, comply with the requirements of ASTM C 171.

5.2.5 Cold Weather Requirements: When concrete is to be placed under or exposed to cold weather conditions, a description of the materials and methods proposed for protection of the concrete shall be furnished for approval by the Contracting Officer.

6. MATERIAL DELIVERY, STORAGE AND HANDLING:

6.1 Cementitious Materials:

6.1.1 Transportation: When bulk cement or pozzolan is not unloaded from primary carriers directly into weather tight hoppers at the batching plant, transportation from the railhead, mill or intermediate storage to the batching plant shall be accomplished in adequately designed weather tight trucks, conveyors or other means that will protect the cement or pozzolan completely from exposure to moisture.

6.1.2 Storage: Immediately upon receipt at the site of the work, cementitious materials shall be stored in a dry, weather tight and properly ventilated structure. All storage facilities shall be subject to approval and shall be such as to permit easy access for inspection and identification.

Sufficient cementitious materials shall be in storage to sustain continuous operation of the concrete mixing plant while pavement is being placed. To prevent cement from becoming unduly aged after

2515- 5 delivery, the Contractor shall use any cement that has been stored at the site for 60 days or more before using cement of lesser age.

6.1.3 Separation of Materials: Separate facilities shall be provided for unloading, transporting, storage and handling each type of cementitious material.

6.2 Aggregates:

6.2.1 Storage: Aggregate shall be stored at the site of the batching plant in a manner to avoid breakage, segregation or contamination by foreign materials. Each size of aggregate from each source shall be stored separately in free-draining stockpiles. Fine aggregate and the smaller size of coarse aggregate shall remain in free-draining storage for at least 48 hours immediately prior to use. Sufficient aggregate shall be maintained at the site at all times to permit continuous uninterrupted operation of the mixing plant while concrete is being placed.

6.2.2 Handling: Aggregate shall be handled in a manner to prevent segregation. Vehicles used for stockpiling or moving aggregate shall be kept clean of foreign materials. Stockpiles shall be worked in a manner to prevent different sizes of aggregate from being mixed during storage or loading of batching hoppers.

7. NOT USED

8. MATERIALS:

8.1 Cements:

8.1.1 General: Cement and pozzolan may be furnished in bulk or packages. When cement is furnished in packages, mixing batch proportions shall be adjusted to require complete packages of cement.

8.1.2 Portland Cement: Portland Cement shall conform to ASTM C 150, Type I. Include the cement certification as part of the concrete mix design.

8.1.3 Pozzolan: Pozzolan shall conform to ASTM C 618, Class N, except that the values below shall be used in lieu of those provided in Tables 1 and 2 of ASTM C 618.

TABLE 1

Mineral Admixture Class N

TABLE 2

Mineral Admixture Class N

Loss on Ignition, Percent, Max. 8.0

Pozzolanic Activity Index with lime @ 7 days min, psi 900

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8.1.4 Temperature: The temperature of the cement and pozzolan as delivered to storage at the site, shall not exceed 150 degrees F.

8.2 Admixtures:

8.2.1 Air-Entraining Admixtures

: The air-entraining admixture shall conform to ASTM C 260 and shall consistently entrain the air content in the specified ranges under field conditions. The air-entraining admixture shall be in a solution of suitable viscosity for field use.

8.2.2 Accelerator: Calcium chloride shall not be used.

8.2.3 Retarder: A retarding admixture shall meet the requirements of ASTM C 494, Type B, except that the six-month and one-year compressive strength tests are waived. The use of the admixture is at the option of the Contractor.

8.2.4 Water-Reducer: A water-reducing admixture shall meet the requirements of ASTM C 494 Type A or D except that the six-month and one-year compressive strength tests are waived. The admixture may be added to the concrete mixture only when its use is approved or directed by the Contracting Officer or designated representative.

8.3 Curing Materials:

8.3.1 Impervious sheet materials shall conform to ASTM C 171, type optional, except polyethylene film, if used, shall be white opaque.

8.3.2 Membrane-forming curing compounds shall be white

pigmented compounds conforming to

COE CRD C-300.

8.4 Dowels: Dowels shall be fabricated or cut to length at the shop or mill before delivery to the site.

Dowels shall be free of loose flaky rust and loose scale and shall be clean and straight. Dowels may be sheared to length provided that the deformation from true shape caused by shearing does not exceed 0.04 inch on the diameter of the dowel and does not extend more than 0.04 inch from the end of the dowel. Dowels shall be plain steel bars conforming to ASTM A 615, grade 40 or 60; ASTM A 616, grade 50 or 60; or ASTM A 617, grade 40 or 60. Dowels shall be 1" diameter by 20" long installed at 12" on center. Include dowel mill report for approval by the Contracting Officer.

8.5 Joint Filler:

8.5.1 For Expansion Joints: Filler shall be preformed materials conforming to ASTM D 1751.

8.5.2 For Contraction Joints: Sawable type contraction joint inserts shall conform to ASTM D 2828.

Non-sawable contraction joint inserts shall have sufficient stiffness to permit placement in plastic concrete without undue deviation from a straight line and shall conform to the physical requirements of ASTM D 2828, with the exception of Section 3.4, "Resistance to Sawing."

8.6 Reinforcement: All reinforcement shall be free from loose flaky rust, loose scale, oil, grease, mud or other coatings that might reduce the bond with concrete. Removal of thin powdery rust and tight rust is not required. However, reinforcing steel which is rusted to the extent that it does not conform to the required dimensions or mechanical properties shall not be used. Include rebar

2515- 7 mill report for approval by the Contracting Officer.

8.6.1 Bar Mats: Bar mats shall conform to ASTM A 184. The bar members shall be billet steel.

8.6.2 Wire Fabric: Welded steel wire fabric shall conform to ASTM A 185.

8.6.3 Deformed Wire Fabric: Welded deformed steel wire fabric shall conform to ASTM A 487.

8.7 Tie Bars: Tie bars shall be deformed steel bars conforming to ASTM A 615, A 616 or A 617, and of the sizes and dimensions indicated. Deformed rail steel bars and high-strength billet or axle steel bars, grade 60 or higher, shall not be used for bars that are bent and straightened during construction.

8.8 Epoxy Resin: All epoxy resin materials shall be two-component materials conforming to the requirements of ASTM C 881, class as appropriate for each application temperature to be encountered, except that in addition, the materials shall meet the following requirements:

8.8.1 All materials shall have a 24-hour absorption not greater than one percent.

8.8.2 The materials for bonding freshly mixed Portland Cement concrete or mortar or freshly mixed epoxy resin concrete or mortar to hardened concrete shall be Type II materials, grade as permitted by the Contracting Officer or designated representative.

8.8.3 The materials for use as patching materials for complete filling of spalls, wide cracks and other voids; for use for embedding dowels and anchor bolts; and for use as a binder in preparing epoxy resin mortars and concretes shall be Type III materials and shall in addition meet these requirements: (a) the bond strength at 14 days (moist cure) shall be at least 1,000 psi, and (b) the volatile content, cured system, shall not exceed 3 percent. Grade shall be as approved except that Grade 3 shall be used for embedding dowels in hardened concrete.

8.9 Water: Water for washing aggregates and for mixing and curing concrete shall be fresh and free from injurious amounts of oil, acid, salt, alkali, organic matter or other deleterious substances.

Coarse Aggregate

8.10 Coarse Aggregate

8.10.1 Composition: Coarse aggregate shall consist of crushed or uncrushed gravel, crushed stone, or a combination thereof. Crushed gravel shall contain at least 75 percent double face fracture of the coarse aggregate by weight in each sieve size.

8.10.2 Quality: Aggregates as delivered to the mixers shall consist of clean, hard uncoated particles meeting the requirements of ASTM C 33. Dust and other coating shall be removed from the coarse aggregates by washing.

8.10.3 Particle Shape: Particles of the coarse aggregate shall be generally spherical or cubical in shape. The quantity of flat and elongated particles in any size group shall not exceed 20 percent by weight. A flat particle is defined as one having a ratio of width to thickness greater than three; an elongated particle is one having a ratio of length to width greater than three.

2515- 8

8.10.4 Size and Grading: The nominal maximum size coarse aggregate shall be one inch or less, and the coarse aggregates shall be furnished in one size groups as follows:

8.10.5 The grading of the coarse aggregate within the separated size groups, when tested in accordance with ASTM C 136, shall conform to the following requirements as delivered to the mixer:

COURSE AGGREGATE GRADATIONS

Combined Grading

8.10.6 Combined Concrete Aggregate Gradation: In addition to the grading requirements specified for coarse aggregate and for fine aggregate, the combined aggregate grading shall meet the following requirements:

8.10.6.1 When necessary, a blending aggregate shall be used to meet the required combined grading. This blending aggregate shall be batched separately.

8.10.6.2 The combined grading of all aggregates used, in the proportions selected, shall be computed on the basis of cumulative percent retained on each sieve specified for fine and coarse aggregate.

8.10.6.3 The materials selected and the proportions used shall be such that when the Coarseness Factor (CF) and the Workability Factor (W) are plotted on a diagram as described in below, the point thus determined shall fall within the parallelogram described below.

8.10.6.4 The Coarseness Factor (CF)

shall be determined from the following equation: (CF) = (cumulative percent retained on the 3/8 in. sieve)*(100) / (cumulative percent retained on the No. 8 sieve).

8.10.6.5 The Workability Factor (W)

Maximum is defined as the cumulative percent passing the No. 8 sieve.

Nominal Size Size Group

Inches 1" No. 4 to 1 inch

3/4" No. 4 to 3/4 inch

Sieve No.4 to No.4 to Size 3/4 inch 1 inch 2”

1-1/2” 100 1” 100 94-100

3/4” 90-100 --- 1/2” --- 23-63 3/8” 20-54 --- #4 1-10 0-10 #8 0-6 0-6

2515- 9

However, (W) shall be adjusted, upwards only, by 2.5 percentage points for each 94 pounds of cementitious material per cubic yard greater than 564 pounds per cubic yard.

8.10.6.6 A diagram shall be plotted using a rectangular scale with (W) on the Y-axis with units from 20 (bottom) to 45 (top), and with (CF) on the X-axis with units from 80 (left side) to 30 (right side).

On this diagram a parallelogram shall be plotted with corners at the following coordinates (CF-75, W-28), (CF-75, W-40), (CF-45, W-32.5), and (CF-45, W-41). If the point determined by the intersection of the computed (CF) and (W) does not fall within the above parallelogram, the grading of each size of aggregate used and the proportions selected shall be changed as necessary.

8.10.6.7 In addition, the individual percent retained on each sieve shall be plotted for the combined aggregate grading, on either rectangular or semi-log graph paper. The graph shall show a relative smooth transition between coarse and fine aggregate and shall have no major valleys or peaks in the area smaller than the No. 8 sieve. If this plot does not meet the above criteria, the grading of each size aggregate used and the proportions selected shall be changed as necessary.

8.10.6.8 The following gradation of coarse aggregates combined with fine aggregates is an example of a concrete aggregate gradation with a maximum nominal size of 3/4":

CONCRETE AGGREGATE GRADATIONS

Sieve Size/Percent Passing

3/4" - 100%, 1/2" - 78-90% , 3/8" - 52-64%, #4 - 29-41%, #8 - 24-36%, #16 - 16-28%, #30 - 8-20%, #50 - 6-12%, #100 - 2-8%.

FM 2.805

Deleterious Substances

8.10.7 Deleterious Substances: The amount of deleterious substances in each size group of coarse aggregate shall not exceed the limits shown below, determined in accordance with ASTM C 117, ASTM C 123, ASTM C 295, ASTM C 851, applicable only to material coarser than 3/8-inch and

ASTM C 142.

LIMITS OF MATERIALS FOR AIRFIELD PAVEMENTS

Percentage Materials By Weight Clay lumps 0.2 Shale (1) 0.1 Material finer than #200 0.5 Lightweight particles (3) 0.2 Clay ironstone (4) 0.1 Chert and cherty stone (less than 2.40 specific gravity SSD) (5) 0.1 Claystone, mudstone and siltstone (6) 0.1 Shaly and argillaceous Limestone (7) 0.2

Other soft particles 1.0 Total of all deleterious substances exclusive of material finer 1.0 than No.

200 sieve

(1) Shale is defined as a fine-grained thinly laminated or fissile sedimentary rock. It is commonly composed of clay or silt or both. It has been indicated by compaction or by cementation, but not so much as to have become slate.

2515- 10

(2) Limit for material finer than No. 200 sieve will be increased to 1.5 percent for crushed aggregates if the fine material consists of crusher dust that is essentially free from clay or shale.

(3) The separation medium shall have a specific gravity of 2.0. This limit does not apply to coarse aggregate manufactured from blast-furnace slag unless contamination is evident.

(4) Clay ironstone is defined as an impure variety of iron carbonate, iron oxide, hydrous iron oxide or combinations thereof, commonly mixed with clay, silt or sand. It commonly occurs as dull, earthy particles, homogeneous concretionary masses or hard shell particles with soft interiors.

Other names commonly used for clay ironstone are "chocolate bars" and limoite concretions.

(5) Chert is defined as a rock composed of quartz, chalcedony or opal or any mixture of these forms of silica. It is variable in color. The texture is so fine that the individual mineral grains are too small to be distinguished by the unaided eye. Its hardness is such that it scratches glass but is not scratched by a knife blade. It may contain impurities such as clay, carbonates, iron oxides and other minerals. Other names commonly applied to varieties of chert are: flint, jasper, agate, onyx, hornstone, porcellanite, novaculite, sard, carnelian, plasma, bloodstone, touchstone, chrysoprase, heliotrope and petrified wood. Cherty stone is defined as any type of rock (generally limestone) that contains chert as lenses and nodules, or irregular masses partially or completely replacing the original stone.

(6) Claystone, mudstone, or siltstone is defined as a massive fine-grained sedimentary rock that consists predominantly of clay or silt without laminations or fissility. It may be indicated either by compaction or by cementation.

(7) Shaly limestone is defined as a limestone in which shale occurs as one or more thin beds or laminae. These laminae may be regular or very irregular and may be spaced from a few inches down to minute fractions of an inch. Argillaceous limestone is defined as a limestone in which clay minerals occur disseminated in the stone in the amount of 10 to 50 percent by weight of the rock;

when these make up from 50 to 90 percent, the rock is known as clacareous (or dolomitic) shale (or claystone, mudstone or siltstone).

Fine Aggregate

8.11 Fine Aggregate

8.11.1 Composition: Fine aggregate shall consist of natural sand, manufactured sand or a combination of the two, and shall be composed of clean, hard, durable particles.

8.11.2 Particle Shape: Particles of the fine aggregate shall be generally spherical or cubical in shape.

8.11.3 Grading: Grading of the fine aggregate, as delivered to the mixer, shall have a fineness modules of not less than 2.40 nor more than 2.90.

The grading of the fine aggregate also shall be controlled so that the fineness moduli of at least nine of ten samples of the fine aggregate, as delivered to the mixer, will not vary more than 0.15 from the average fineness moduli of all samples previously taken.

8.11.4 Deleterious Substances: The amount of deleterious substances in the fine aggregate shall not exceed the following limits:

2515- 11

The total of all deleterious materials shall not exceed 3.0 percent of the weight of the aggregate.

9.0 NOT USED.

10.0 PRODUCTION OF CONCRETE:

10.1 Location of Plant: Concrete batching plant is permitted at the on-JBER gravel extraction site.

10.2 Capacity: Each concrete mixer shall have a capacity of not less than 5 cubic yards. Batching, mixing and hauling equipment shall have a capacity sufficient to maintain a forward movement of the paver of not less than 2.5 fpm.

10.3 Batching Plant: The batching plant shall conform to the requirements of CRD-C 95 and as specified; however, rating plates attached to batch plant equipment are not required.

10.3.1 Equipment: The batching controls shall be either semiautomatic or automatic.

Semiautomatic batching system shall be provided with interlocks. Separate bins or compartments shall be provided for each size group of aggregate and pozzolan and cement. If both cement and pozzolan are used, they may be batched cumulatively provided Portland Cement is batched first. If measured by weight, water shall not be weighed cumulatively with another ingredient. Water batcher filling and discharging valves shall be so interlocked that the discharge valve cannot be opened before the filling valve is fully closed. An accurate mechanical device for measuring and dispensing each admixture shall be provided. Each dispenser shall be interlocked with the batching cycle and discharged automatically in a manner to obtain uniform distribution throughout the batch in the specified mixing period. Where use of truck mixers makes this requirement impracticable, the admixture dispensers shall be interlocked with the sand batches. Admixtures will not be combined before introduction in sand or water. The plant shall be arranged so as to facilitate the inspection of all operations at all times. Suitable facilities shall be provided for obtaining representative samples of aggregates from each bin or compartment.

10.3.2 Scales: Adequate facilities shall be provided for the accurate measurement and control of each of the materials entering each batch of concrete. The weighing equipment shall conform to the applicable requirements of NIST Handbook 44, except that the accuracy shall be within 0.2 percent of scale capacity. The Contractor shall provide standard test weights and any other auxiliary equipment required for checking the operating performance of each scale or other measuring device. Each weighing unit shall include a visible springless dial, which shall indicate the scale load at all stages of the weighing operation or shall include a beam scale with a beam balance indicator that will show the scale in balance at zero load and at any beam setting. The indicator shall have an over and under travel equal to at least five percent of the capacity of the beam. The weighing

Material Percentage by Weight Clay lumps and friable particles Material finer than #200 sieve

Lightweight particles

1.0 3.0 0.5

Percentage of Required Percentage of Scale Materials Weight Capacity Cement (and Pozzolan) Aggregate Water Admixture

Plus or minus 0.3% Plus or minus 2% Plus or minus 1% Plus or minus 3%

Plus or minus 0.3% Plus or minus 0.3%

2515- 12 equipment shall be arranged so that the concrete plant operator can conveniently observe the dials or indicators.

10.3.3 Batching Tolerances:

10.3.3.1 Weighing Tolerances: Whichever of the following tolerances is greater shall apply, based on required scale reading:

10.3.3.2 Volumetric Tolerances: For volumetric batching equipment, the tolerances that shall apply to the required volume of material being batched are:

(a) water-plus or minus one percent, and

(b) admixtures-plus or minus three percent.

10.3.4 Moisture Control: The plant shall be capable of ready adjustment to compensate for the varying moisture contents of the aggregates and to change the weights of the materials being batched. An electric moisture meter shall be provided for measuring of moisture in the fine aggregate. The sensing element shall be arranged so that measurement is made near the batcher charging gate of the sand bin or in the sand batcher.

10.4 Concrete Mixers:

10.4.1 General: The mixers shall not be charged in excess of the capacity recommended by the manufacturer. The mixers shall be operated at the drum or mixing blade speed designated on the manufacturer's data plate. The mixers shall be kept free of hardened concrete. Should any mixer at any time produce unsatisfactory results, its use shall be promptly discontinued until it is repaired.

10.4.2 Central Plant Mixers: Central plant mixers shall be tilting, non-tilting, or vertical-shaft type and shall be provided with an acceptable device to lock the discharge mechanism until the required mixing time has elapsed.

10.4.3 Mixing Time and Uniformity: For concrete plant mixers, in the absence of uniformity data, the mixing time for each batch after all solid materials are in the mixer, provided that all of the mixing water is introduced before one-fourth of the mixing time has elapsed, shall be one minute for mixers having a capacity of one cubic yard. For mixers of greater capacity, this minimum time shall be increased 15 seconds for each additional cubic yard or fraction there-of. These mixing times are predicted on operation at a designated speed and proper introduction of materials into the mixer. The mixing time may be reduced, if so approved, to the minimum time required to meet all the uniformity requirements. Mixer performance tests at the proposed reduced mixing times

Percentage of Required Percentage of Scale Materials Weight Capacity Cement (and Pozzolan) Aggregate Water Admixture

Plus or minus 0.3% Plus or minus 2% Plus or minus 1% Plus or minus 3%

Plus or minus 0.3% Plus or minus 0.3%

2515- 13 shall be performed, and the mixer shall meet the following requirements when tested as required in the paragraph INDEPENDENT QUALITY CONTROL.

10.4.4 Truck Mixers:

10.4.4.1 Each truck shall be permanently marked with the volume of mixed concrete and the mixing and agitating speeds. Each truck shall be equipped with counters to determine the number of revolutions at mixing and agitating speeds. Concrete completely mixed in a truck mixer shall be mixed 70 to 100 revolutions at a designated mixing speed after all ingredients including mixing water have been charged into the drum.

10.4.4.2 Concrete first partially intermingled in a concrete plant mixer (shrink-mixed) a minimum time as required to combine the ingredients shall then be completely mixed in a truck mixer. The number of revolutions between 70 and 100 for truck-mixed concrete and the number of revolutions for shrink-mixed concrete shall be determined by uniformity tests as specified in requirements for mixer performance stated in paragraph INDEPENDENT QUALITY CONTROL. If requirements for the uniformity of concrete are not met with 100 revolutions of mixing after all ingredients including water are in the drum, the mixer shall not be used until the condition is corrected.

Additional revolutions beyond the number determined to produce the required uniformity shall be at a designated agitating speed.

10.4.4.3 Water shall not be added after the initial introduction of mixing water, except when on arrival at the jobsite the slump is less than specified and the water-cement ratio is less than the approved mixture design permits. Additional water may be added to bring the slump within the specified range provided the approved water-cement ratio is not exceeded. Water shall be injected into the mixer under pressure, and the drum or blades shall be turned a minimum of 30 additional revolutions at mixing speed. Water shall not be added to the batch at any later time.

11. TRANSPORTING EQUIPMENT:

11.1 Transportation of concrete mixed completely in a stationary mixer from the mixer to the point of placement shall be by truck agitator, in a truck mixer operating at agitator speed, or in non-agitating equipment. All transporting equipment shall conform to ASTM C 94, except as modified herein.

11.2 Vehicles transporting concrete mixed partially or completely in stationary mixers and truck mixers used for complete concrete mixing shall be capable of delivering and discharging the concrete without segregation. Equipment shall be provided that is capable of transferring the concrete from the transporting vehicle and distributing the concrete without segregation into its final position.

11.3 The transfer and distribution of the concrete shall be by a mechanical spreader or by a concrete bucket and crane. The surface on which the pavement is being placed shall be maintained free from foreign materials or concrete that has begun to harden.

12. PLACING:

12.1 General: Concrete may be placed between stationary forms, or may be constructed to the desired cross section using slip form pavers. Concrete shall be deposited between the forms or placed with the slip form paver within 90 minutes from the time cement has been charged into the

2515- 14 mixing drum of the truck mixer. Concrete shall be deposited as close as possible to its final position in the pavement cross section. The placement of the concrete shall be continuous and at a uniform rate without unscheduled stops except for equipment failure or other emergencies. Workmen with foreign material on their footwear or construction equipment that might deposit foreign material shall not be permitted to walk or operate in the concrete during placement and finishing operations.

12.2 Slip form Method: The slip form paver shall be self-propelled automatically controlled, crawler-mounted and capable of spreading, consolidating and shaping the plastic concrete to the desired cross section in one pass. The paver shall be capable of finishing the surface and edges so that a minimum amount of hand finishing is required, and shall have sufficient weight and power to handle the amount of concrete required for the full-lane width as specified. The mechanisms for forming the pavement shall be easily adjustable in width and thickness. Horizontal alignment shall be referenced to a taut wire or string line. Vertical alignment shall be referenced to a taut wire or string line, to the surface of the underlying material, or to the surface of previously constructed pavement. The vibrators or tamping elements shall be automatically controlled so that they shall be stopped as forward motion ceases. When the paver approaches a header at the end of a paving lane, a sufficient amount of concrete shall be maintained ahead of the paver to allow a roll of concrete to spill over the header. The amount of extra concrete shall be sufficient to prevent the slurry that is formed and carried along ahead of the paver from being deposited adjacent to the header. The spud vibrators on the front of the paver should be brought as close to the header as possible before they are lifted. Additional consolidation shall be provided adjacent to the headers by hand-manipulated vibrators. When the slip form paver is operated between or adjacent to previously constructed pavements, provisions shall be made to prevent damage to the previously constructed pavement. Transversely oscillating screeds shall be electronically controlled from the previously placed pavement to prevent the screed from applying pressure to the existing pavement. When the paver travels on existing pavement, provisions shall be made to prevent damage to the existing pavement. Slip form pavers using transversely oscillating screeds shall not be used to form fill-in lanes that have widths less than a full width for which the paver was designed.

12.3 Spreading:

12.3.1 Spreading shall be by machine method, except when transporting equipment is permitted on the underlying material, in which case the concrete may be discharged directly in front of the paver. When placed directly in front of the paver, the concrete shall be spread evenly across the full width of the paving lane. Hand spreading will be permitted only where required for odd widths or shapes of slabs. Hand spreading shall be done with shovels; rakes shall not be used.

12.3.2 Mechanical spreaders shall be designed and operated to distribute the plastic concrete uniformly across the full width of the paving lane. Machines that cause displacement of properly installed forms or ruts or indentations in the prepared underlying material and machines that cause frequent delays due to mechanical failures shall be replaced as directed.

12.3.3 When the spreader rides the edges of previously constructed lanes, provisions shall be made to prevent damage to the previously constructed pavement.

12.3.4 Where concrete is delivered to the form in truck mixers, suitable chutes may be used, provided windrows cover essentially the entire area within the form. In no case is the dumping of concrete at one location and the running into place with vibration permitted.

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12.3.5 The spreading of concrete shall be performed at such elevations, slightly above grades, that when properly consolidated the surface will be at the elevation indicated.

12.4 Vibration:

12.4.1 Concrete shall be consolidated with mechanical vibrating equipment immediately after spreading. Vibrating equipment shall be of the internal type, and the number of units and the power of each unit shall be adequate to properly consolidate the concrete with the vibration spacing used.

12.4.2 The vibrating unit shall be mounted on a frame or on the paver and equipped with suitable controls so that all vibrators may be operated at any desired depth within the slab or completely withdrawn from the concrete, as required. The spacing of vibrating units that extend into the slab at intervals across the paving lane shall be as necessary to properly consolidate the concrete, but the clear distance between the units shall not exceed 30 inches.

12.4.3 The outside elements of the internal spud vibrator units shall be approximately one foot from the edge of the slab. Vibrators of this type shall be inserted into the concrete to a depth that will provide the best consolidation but not closer to the underlying material than two inches.

12.4.4 Concrete in odd-shaped slabs or in locations inaccessible to the vibrating equipment above shall be vibrated with a hand-manipulated vibrator.

12.4.5 Vibrators shall not be used to transport or spread the concrete in the forms.

12.4.6 Spud vibrators shall operate at a frequency of not less than 8,000 impulses per minute and tube vibrators at a frequency of not less than 5,000 impulses per minute when in the concrete.

Excessive vibration will not be permitted. Vibrators shall not be operated in the concrete at one location for more than 20 seconds.

12.4.7 Forward motion of the paver shall cease as soon as a vibrator becomes inoperable and shall not start until the vibrator is repaired or replaced. At least one additional vibrator or sufficient parts for replacing and repairing vibrators or vibrator assemblies for each paving train, shall be maintained at the site at all times.

12.5 Placing Reinforcing Steel: The type and amount of steel reinforcement shall be 6x6-6x6 welded wire fabric. The welded wire fabric shall be properly positioned during concrete placement. Wire fabric and deformed wire fabric reinforcement shall be placed to its correct position by suitable vibratory equipment after the first lift of concrete has been placed. The reinforcing steel shall be free from coatings that could impair bond between the steel and the concrete, end laps in the reinforcement shall be as indicated.

12.6 Placing During Cold Weather

: Concrete placement shall be discontinued when the air temperature reaches 40 F and is falling. Placement may begin when the air temperature reaches 40 F and is rising. Provision shall be made to protect the concrete from freezing during the specified curing period. If necessary to place concrete when the temperature of the air, aggregates or water is below 40 F, placement shall be approved in writing.

12.6.1 Approval shall be contingent upon full conformance with the following provisions. The underlying material shall be prepared and protected so that it is entirely free of frost when the

2515- 16 concrete is deposited. Mixing water and aggregates shall be heated as necessary to result in the temperature of the in-place concrete being between 50 F and 85 F. Methods and equipment for heating shall be approved. The aggregates shall be free of ice, snow and frozen lumps before entering the mixer.

12.6.2 Covering with insulation blankets or other means shall be provided for maintaining the concrete at a temperature of at least 50 degrees F for not less than 72 hours after placing, and at a temperature above 40 F for the remainder of the 7 day curing period.

12.6.3 Provide cold weather protection IAW ACI 306R "Cold Weather Concreting" and submit the cold weather plan for approval to the Contracting Officer. Concrete damaged by freezing or freeze/thaw cycles shall be removed and replaced as specified in paragraph REMOVAL AND

REPLACEMENT OF DEFECTIVE PAVEMENT AREAS.

12.7 Placing During Hot Weather: During periods of hot weather when the maximum daily air temperature is likely to exceed 85 F, the following precautions shall be taken. The forms and the underlying material shall be sprinkled with water immediately before placing the concrete.

Concrete shall be placed at the coolest temperature practicable, and in no case shall the temperature of the concrete when placed exceed 90 F. Aggregates and mixing water shall be cooled as necessary. Concrete shall be placed continuously and rapidly at a rate of not less than 100 feet of paving lane per hour. The finished surfaces of the newly laid pavement shall be kept damp by applying a water fog or mist with approved spraying equipment until the pavement is covered by the curing medium. If necessary, wind screens shall be provided to protect the concrete from an evaporation rate in excess of 0.2 psi per hour.

13. FINISHING:

13.1 Finishing operations shall be started immediately after placement of the concrete. Finishing shall be by the machine method except that where indicated, the hand method will be permitted on odd slab widths or shapes and in event of breakdown of the mechanical equipment to finish concrete. The sequence of operations shall be finishing, floating, straightening, texturing and then edging of joints. Finishing equipment and tools shall be maintained clean and in an approved condition.

13.2 Machine Finishing with Fixed Forms:

13.2.1 Equipment: The finishing machines shall be of ample weight and power for proper finishing of the concrete. The finishing machine shall be designed and operated to strike off, screed and consolidate the concrete. Screed and float adjustments of these machines shall be checked at the start of each day's paving operations and more often as required. Machines that cause displacement of side forms or that cause frequent delays due to mechanical failure shall be replaced. When finishing machines ride the edge of a previously constructed slab, provision shall be made to protect the surface of these slabs.

13.2.2 Transverse Finishing: As soon as placed, the concrete shall be accurately struck off and screeded to the crown and cross section shown and to such elevation that when consolidated and finished, the surface of the pavement will be free from porous places and will be at the required grade. The finishing machine shall make as many trips over each area of pavement as necessary to compact the concrete and produce a surface of uniform texture, true to grade. Water shall not be added to the concrete used to fill low spots or to facilitate finishing operations. Excessive manipulation that brings mortar and water in excess of 1/8-inch thick to the surface will not be

2515- 17 permitted, and any equipment that cannot produce the required compaction and surface finish without an excessive number of trips will be considered unsatisfactory. The top of the form or pavement edge upon which the finishing machine travels shall be kept clean.

13.2.3 Mechanical Floating: After completion of screeding, the mechanical float may be operated to smooth and finish the pavement to grade. The float shall be operated so as to maintain contact with the surface at all times. If required, additional concrete shall be placed and screeded, and the float operated over the same area until a satisfactory surface is produced.

13.2.4 Other Types of Finishing Equipment: Concrete finishing equipment of types other than specified above may be used on a trial basis. The use of equipment that fails to produce finished concrete of the quality and consistency required by these specifications shall be discontinued, and the concrete shall be finished with approved equipment and in a manner specified above.

13.3 Finishing by Slip form Method: The slip form paver shall be capable of finishing the surface and edges so that only a minimum of additional work is necessary. A self-propelled pipe float may be used if the Contractor desires, while the concrete is still plastic, to remove minor irregularities and score marks. Straightedge finishing may be used as required; however, its use shall be kept to a minimum. The pipe float shall be six to ten inches in diameter and sufficiently long to span the full paving width when oriented at an angle of approximately 60 degrees with the center line. Pipe floating should be accomplished as soon as possible and discontinued immediately after a uniform surface appearance is achieved. Concrete slurry permitted to run down the vertical edges of the slipped concrete will be removed by hand, using stiff brushes or other approved scrapers. Concrete slurry will not be used to build up along the edges of the concrete to compensate for excessive edge slump. Wood or metal forms shall be available for use in repairing edges that slough excessively.