Atch_15_Spec_Section_32_13_11_PCC_Airfield.doc

PAVING IDIQ

Solicitation: FA4861-16-R-A300

RIGID CONCRETE PAVEMENT FOR AIRFIELDS

SECTION 32 13 11

1. PART 1 - GENERAL

1.1. APPLICABLE PUBLICATIONS: The publications listed below form a part of this specification. The publications are referred to in the text by basic designation only.

Department of the Army, Corps of Engineers, Handbook for Concrete and Cement:

CRD-C 55-91

Concrete Within Batch Uniformity (used for determination of the minimum time of mixing)

CRD-C 119-91

Flat and Elongated Particles in Coarse Aggregate (Rev Jun 1963)

CRD-C 400-63

Water for Use in Mixing or Curing Concrete

American Society for Testing and Materials (ASTM) Publications:

A 120-84

Pipe, Steel, Black and Hot-Dipped Zinc- Coated (Galvanized) Welded and

Seamless, for Ordinary Uses

A l84/A 184M-90 Fabricated Deformed Steel Bar Mats for Concrete Reinforcement

A l85-94

Steel Welded Wire Fabric, Plain

A 497-94a

Welded Deformed Steel Wire Fabric for Concrete Reinforcement

A 6l5/A 615M-95b Bars, Deformed and Plain, Billet-Steel, for Concrete Reinforcement

A 6l6/A 616M-95b Bars, Deformed and Plain, Rail Steel, for Concrete Reinforcement

A 617/A 617M-95b Bars, Deformed and Plain, Axle-Steel, for Concrete Reinforcement

ACI305R-91

Hot Weather Concreting

C 3l-91

Making and Curing Concrete Test Specimens in the Field

C 33-93

Concrete Aggregates

C39-94

Compressive Strength of Concrete Cylinders

C 70-94

Surface Moisture in Fine Aggregate (R 1985)

C 75-87

Standard Practice for Sampling Aggregates

C 78-94

Flexural Strength of Concrete Using Simple Beam withThird-Point Loading

C-88-90

Test Method for Soundness of Aggregates by Use of Sodium Sulfate or

Magnesium Sulfate

C l23-94

Lightweight Pieces in Aggregate

C-127-88

Standard Test Methods for Specific Gravity and Absorption of Coarse

Aggregate

C-128-93

Standard Test Methods for Specific Gravity and Absorption of Fine

Aggregate

C-131-89

Resistance to Degradation of Small Size Coarse Aggregate by the Los

Angeles Abrasion Machine

C l36-95a

Sieve Analysis of Fine and Coarse Aggregates

C l42-78 (1990) Clay Lumps and Friable Particles in Aggregates (R 1990)

C l50-95

Portland Cement

C 172-90

Sampling Freshly Mixed Concrete

C 23l-91b

Air Content of Freshly Mixed Concrete by the Pressure Method

C 260-94

Air-Entraining Admixtures for Concrete

C 289-94

Potential Alkali-Silica Reactivity of Aggregates

C 295-90

Petrographic Examination Aggregates for Concrete

C 309-94

Liquid Membrane-Forming Compounds for Curing Concrete

C 311-94b

Sampling and Testing Flyash or Natural Pozzolansfor use as a Mineral

Admixture

C 494-92

Chemical Admixtures for Concrete

C 535-89

Resistance to Degradation of Large Size Coarse Course Aggregate in the Los

Angeles Abrasion Machine

C 566-89

Total Moisture Content of Aggregate by Drying

C 595M - 95

Blended Hydraulic Cements

C 618-89a

Fly Ash and Raw or Natural Pozzolan for Use as a Mineral Admixture in

Portland Cement Concrete

C 881-90

Epoxy-Resin-Base Bonding Systems for Concrete

C 1064 - 86

Temperature of Freshly Mixed Portland Cement Concrete

D 1751

Preformed Expansion Joint Filler for Concrete Paving and Structural

Construction (Nonextruding and Resilient Bituminous Types)

D l752

Preformed Sponge Rubber and Cork Expansion Joint Fillers for Concrete

Paving and Structural Construction

U.S. Department of Commerce, National Bureau of Standards

National Bureau of Standards (NBS) Handbook 44 - Specification, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices.

1.2. ACCEPTANCE TESTING/ QUALITY CONTROL (QC) PROCEDURES:

1.2.1. Acceptance Testing: The Government may supplement the results of the material testing which is accomplished by the Contractor to evaluate construction for acceptance. The Contractor shall provide copies of all QC testing results and daily reports to the Contracting Officer representative within 24-hours of the work represented. The government may elect to supplement the quality control testing with quality assurance testing accomplished by another party.

1.2.2. Quality Control (QC) Testing by Contractor: The Contractor shall perform the Quality Control (QC) functions required by this specification. The QC Laboratory ( QC LAB) shall accomplish concrete mixture proportioning and the daily monitoring of the concrete mixing and placing. The minimum daily monitoring requirements are described within section 3.12.4 CONTRACTOR QUALITY CONTROL, in Part 3 of this specification. Within 15 days after the Notice to Proceed date, the Contractor shall submit a qualifications statement of the proposed QC LAB. The Government will review the qualifications of the laboratory and, if necessary, visit the QC LAB. Evaluation criteria will include respective State or National accrediation and/or certification programs.

1.2.2.1. The Contractor shall retain the services of an independent commercial testing laboratory to perform the QC LAB functions; and/or,

1.2.2.2. The Contractor can use a contractor-owned quality control staff provided that all of the following conditions are met to the satisfaction of the Contracting Officer:

a. The Contractor's quality control function is and has been a part of the orginization for a minimum of 2 years;

b. Each quality control technician is qualified through certification by a national organization, or has a degree in a related engineering field;

c. The quality control manager shall be a full time employee of the Contractor, shall have a minimum of 5 years experience in construction materials testing and shall have authority to stop all work associated with the incorporation of non-conforming materials into the project; and

d. Certification from a State or National entity that the equipment used by the Contractor to perform quality control testing conforms to the applicable testing standards and that calibrations of the testing equipment are current.

1.2.3. Concrete Mixture Proportioning Studies: After the aggregate source is approved, as described in paragraph 1.3 MATERIAL ACCEPTANCE TESTING, below, and at least 30 days before the time when placing of concrete is expected to begin, the QC LAB shall start mixture proportioning studies.

1.2.4. Daily "Pour Agreement": The Contractor, or designated representative, the Government representative, and the QC LAB representative shall sign an agreement at the close of each day of concrete placement. The agreement shall state that the procedures used for the day’s placement meet or exceed the performance demonstrated at the test section and that the next placement may proceed. Any one of the signatory persons may elect to not sign. All signatory members have equal authority. When a signatory member does not sign the reasons shall be stated and the deficiency corrected or agreement shall be made on the corrective action. Those people designated to execute the agreement shall be participants at the test section construction.

1.3. MATERIAL ACCEPTANCE TESTING:

1.3.1. Preconstruction Sampling and Testing:

1.3.1.1. Aggregates: Aggregates shall be produced from sources of the Contractor’s choice. The aggregates shall be tested to determine specific gravity, absorption, Los Angeles abrasion, sulfate soundness, soundness, alkali or carbonate reaction, and organic impurities. A petrographic analysis shall be performed on all aggregates unless there is a record of performance, of at least five years, for the aggregate source.

1.3.1.2. Sampling and Testing: The Contractor shall accomplish aggregate sampling and testing of the aggregates for quality determination. The Government will observe the aggregate sampling. The Contractor shall provide split samples to the Government. All quality testing results shall be provided to the Contracting Officer at least 10 days before starting a mixture proportioning study.

1.3.1.3. Portland Cement: The Contractor shall submit the identity of the cement manufacturer, the engineering and chemical qualities of the cement, and a manufacturer’s statement which states that the cement complies with the intent and requirements of this specification. The contractor, or the supplier, is prohibited from changing cement sources during the progress of the work without submitting the same information which qualified the original source. The submittal shall be made at least 10 days before starting a mixture proportioning study. When the Contractor changes sources of cement, strength testing shall be accomplished as if the work were just beginning.

1.3.1.4. Admixtures: The Contractor may use admixtures. Within 15 days after date of notice to proceed, the Contractor shall provide a listing of all chemical and mineral admixtures proposed for use in the concrete mixture. The Contractor assumes all responsibility for the use of admixtures and the results of that election. All mixture proportioning studies will be accomplished with the proposed admixtures included.

1.3.1.4.1. Chemical Admixtures: The chemical admixtures used in the concrete mixture shall be chemically compatible and shall not result in an adverse chemical reaction when combined with other ingredients. The Contractor shall produce a history of performance when admixtures are being supplied by multiple vendors. High-range water-reducing admixtures are not allowed.

1.3.1.4.2. Mineral Admixtures: The Contractor may only use flyash as a part of the airfield concrete mixture. The Contractor shall submit, within 15 days after date of notice to proceed, data which identifies the source and the characteristics of the flyash proposed for use in the concrete mixture.

1.3.1.5. Curing Compound: At least 30 days before the material will be used on the work, the Contractor shall submit a manufacturer statement which certifies that the material conforms to the intent and requirements of these specifications. The Contractor shall not incorporate the curing compound into the work unless the Contracting Officer has provided specific written acceptance of the product proposed. The Contractor shall provide the Government a one gallon sample from the lot(s) of material used on the work at the beginning of the work.

1.3.1.6. Epoxy-Resin Material: At least 30 days before the material is used, the Contractor shall submit a warrant by the manufacturer that the material conforms to the requirements of these specifications. When epoxy resin arrives at the jobsite, the Government shall sample the material and may either test the sample or retain in storage.

1.4. GRADE AND SURFACE-SMOOTHNESS REQUIREMENTS: The finished surface of pavements shall conform to the elevations provided in the contract drawings. The smoothness requirements of Table 1.4.2 are applicable.

1.4.1. Grade Control: Line and grade shown on contract drawings shall be established and maintained by the Contractor. Elevations of bench marks at the site of work will be determined, established, and maintained by the Government.

1.4.2. Plan Grade: Finished surfaces shall conform to the grade and cross sections indicated on drawings. Deviations from the plan elevation will be permitted only where the proper functioning of drainage, appurtenant structures, or matching to existing pavement elevation is required. The grade controls of Table 1.4.2 shall not be exceeded.

TABLE 1.4.2 GRADE CONTROLS FOR AIRFIELD PAVEMENT

OPERATING SURFACES

Pavement

Longitudinal

Transverse

Category

Runway

Max Grade 1.0%. Maximum 0.167%

Max Grade 1.5% change per 30 linear meters of

Min Grade 1.0% runway.

Taxiway

Max Grade 1.5%. Maximum 1.0% change per 30 linear meters of

Min Grade 1.0% taxiway.

Apron

Min Grade 0.5%

Min Grade 0.5%

Other

Same as Apron

Same as Apron

Notes for Table 1.4.2:

a. On runways, the maximum rate of longitudinal grade change is produced by vertical curves having 185 meter lengths for each percent of algebraic difference between two grades. A grade change is not allowed within the first 915 meters from the runway end.

b. On runways, the transverse grade is to remain constant except at intersections where pavement surfaces must be warped.

c. On taxiways, the minimum distance between two points of intersection for a change in grade is 150 meters. Changes in grade are done using vertical curves.

1.4.3. Surface Smoothness:

1.4.3.1. Surface Smoothness: Finished surfaces shall not deviate from the testing edge of a 12-foot straightedge more than tolerances shown for the respective pavement category in Table 1.4.3.

TABLE 1.4.3. SURFACE-SMOOTHNESS TOLERANCES

Transverse 1/8”

¼”

Transverse 3/16”

3/16”

Transverse ¼”

¼”

1.4.3.2. Edge Slump: Edge slump is the downward movement of the concrete along the pavement edge measured not more than 18” (450 mm) from the free edge. When a slip-form paver is used, 85 percent of the pavement, within a distance of one full slab length, shall have an edge slump less than ¼” (6 mm), and 100 percent of the pavement, within a distance of one full slab length, shall have an edge slump less than 3/8” (9.5 mm). Edge slump will be determined by using the procedures described in paragraph 1.4.4.3 EDGE SLUMP DETERMINATION, below. The use of paving equipment and/or procedures that fail to provide pavement edges within the above limitations shall not be allowed.

1.4.4. Surface Evaluation Techniques: The finished surface shall be evaluated for conformance with the plan grade and surface smoothness and edge slump by the contractor.

1.4.4.1. Equipment: The Contractor shall furnish and keep at the jobsite one 12 foot (3.5 meter) straightedge for each operating paver. The straightedge shall be used for testing the surface smoothness and/or edge slump of placed concrete. Wood shall not be used. The straightedge shall have a flat bottom and shall be adequately rigid to assure accuracy.

1.4.4.2. Surface-Smoothness Determinations: When the concrete is hard enough to walk upon without damage to the surface, but not later than 24 hours after placement, the Contractor shall test the pavement surface for smoothness. The testing will be observed by the Government. Testing shall be accomplished using a 12 foot straightedge which shall be placed to reveal surface irregularities. The entire area of the pavement shall be tested in both the longitudinal and transverse direction. The straightedge shall be held in contact with the surface and moved ahead one-half the length of the straightedge for each successive measurement and continuing across transverse joints.

1.4.4.2.1. Deviations: Deviations from the smoothness criteria caused by the edge slump shall not be considered. Deviations caused by high areas along construction joints shall be considered.

1.4.4.2.2. High Areas: The height of a high area on a pavement surface shall be determined by placing the center of the straightedge at the center of the high area and rocking the straightedge until one end comes in contact with the pavement. With one end of the straight- edge grounded, measure the distance between the pavement surface and the bottom of the straightedge at the opposite end. One-half the measurement will be the high area height.

1.4.4.3. Edge Slump Determination: When the concrete will support walking without damage to the surface, the pavement shall be tested by the contractor with a 12 foot straightedge. The edge slump shall be determined at each free edge of each paving lane. The straightedge will be placed transverse to the direction of paving with the end of the straightedge at the free edge of the paving lane. Measurements will be made at increments of not more than one slab length.

1.4.5. Surface Deficiencies and Corrections:

1.4.5.1. High Areas: High areas shall be reduced by grinding the hardened concrete. Grinding shall only be accomplished when the concrete can support the weight of the equipment without damage to the surface.

1.4.5.2. Excessive Edge Slump: Adding concrete to or otherwise manipulating the fresh concrete shall not be used as a method to correct edge slump. Edge slump shall be corrected by adjustment of the concrete mixture or the paving machine. Where edge slump exceeds the allowable, the placed concrete exceeding the limits of edge slump shall be removed and replaced. Removal shall be done according to paragraph 3.10 REMOVAL AND REPLACEMENT OF DEFECTIVE CONCRETE. Removal shall be across the full width of the pavement lane or to the nearest planned longitudinal joint when multiple lanes are placed. Removal shall be to the nearest planned transverse joints which isolates the edge slump deficiencies.

1.5. EQUIPMENT, AND CONSTRUCTION METHODS ACCEPTANCE:

1.5.1. Plant and Equipment: The Contracting Officer representative retains right of access to Contractor's equipment during the progress of the work. The purpose is to evaluate operation of the plant, verify proportions, temperature, mixing time, and character of the materials. The contractor shall submit descriptions of the equipment proposed for use on the project.

1.5.1.1. Batch Plant and Mixers: The Contractor shall submit detailed specifications of the concrete plant.

1.5.1.2. Transport Equipment: The Contractor shall provide the quantity and description of the equipment proposed for transporting concrete from the mixing plant to the placing equipment.

1.5.1.3. Placing Equipment: The Contractor shall describe the equipment proposed to place concrete.

1.5.1.4. Finishing Equipment: The Contractor shall describe the equipment proposed to finish the surface and the method of surface texturing.

1.5.2. Construction Methods: The Contracting Officer representative will review and approve (or reject) proposed special construction methods which may be necessary because of weather conditions encountered during the work.

1.5.2.1. Cold Weather Requirements: The Contractor shall prepare a cold weather concreting plan which describes the materials and methods to be used by the contractor when protection is required.

1.5.2.2. Hot Weather Requirements: The Contractor shall prepare a plan which describes the methods and materials which shall be used to protect concrete under hot weather conditions. Hot weather conditions shall be assumed to prevail when the surface evaporation rate exceeds 0.2 pounds per square foot per hour as determined by using the chart included in ACI 305R-91, Hot Weather Concreting, Fig 2.1.5All concrete placement shall cease when the temperature of the fresh concrete exceeds 90 degrees F.

1.5.3. Pavement Test Section:

1.5.3.1. Construction Methods: The Contractor shall place a pavement test section, within the limits of the work, at a location agreed to by the Contracting Officer and the contractor. The Contractor shall place and finish concrete using the people, procedures, and equipment which will be used on the work. A minimum of 2 hours of mixing and placing concrete, at anticipated production capacity, shall be incorporated into the test section.

1.5.3.2. Test Section Acceptance: Those individuals designated to execute the daily pour agreements will observe the construction of the test section. When the section is rejected, or portions therof, the cause shall be documented and reasons for rejection provided. The concrete placed within a test section that is not accepted shall be removed and replaced, by the contractor, without cost to the government. The work will not proceed until the contractor can demonstrate the placement and finish of an acceptable test section.

1.6. MATERIAL DELIVERY, STORAGE, AND HANDLING:

1.6.1. Cementitious Materials: Cementitious materials include Portland cement and flyash.

1.6.1.1. Transportation: When bulk cement and/or flyash is transported to the batching plant it shall be transported within a weathertight conveyance that protects the cement and/or flyash from exposure to moisture.

1.6.1.2. Storage: Cementitious materials shall be stored in dry, weathertight, and properly ventilated structure(s). There shall be sufficient cementitious materials in storage at the batch plant to sustain operations for the duration of the planned placement.

1.6.2. Aggregates:

1.6.2.1. Storage: Each size of aggregate, from each source, as defined in the mixture proportioning study, shall be stored separately in free-draining stockpiles. There shall be a sufficient quantity of aggregates at the mixing plant to permit continuous uninterrupted operation for the duration of the planned placement.

1.6.2.2. Handling: Aggregate shall be handled in a manner to prevent segregation and breakage. Vehicles used for stockpiling or moving aggregate shall be kept clean of foreign materials. Aggregates shall be stockpiled upon a stabilized surface which precludes the possibility of introducing earth or foreign debris into the stockpile. Stockpiles found to be contaminated by earth or placed in a manner which allows segregation shall be rejected. Determination of contamination and segregation mitigation shall be accomplished by the signature delegates to the “pour agreement”.

END PART 1 - GENERAL

2. PART 2 - PRODUCTS AND MATERIALS

2.1. PAVEMENT QUALITY AIRFIELD CONCRETE MIXTURES: Materials used for the concrete mixture shall include Portland cement, admixtures (chemical and/or mineral selected by the contractor), aggregate, and water. The proportions of the mixture shall be determined by the contractor.

2.1.1. Portland-Cement: Portland cement shall conform to ASTM C-150, Type V and shall be delivered to the site of the mixing plant in dry sealed containers. The temperature of the cement as delivered to the site of the mixing plant shall not exceed 150 degrees Fahrenheit.

2.1.2. Admixtures: The use of chemical and/or mineral admixtures is the option of the contractor, subject to review and acceptance by the Contracting Officer. When admixtures are used they shall be incorporated into all mixture proportioning studies.

2.1.2.1. Chemical Admixtures: Admixtures shall comply with the requirements of ASTM C 260 or ASTM C 494 and shall be compatible with other mixture components. The addition of the admixtures shall not result in a chemical reaction or change in physical properties of the concrete mixture that are adverse to pavement-quality concrete.

2.1.2.2. Mineral Admixture: Flyash may be a component when used as a mineral admixture. It shall conform to ASTM C 618, Class F. When flyash is used, there shall be a minimum cement content of 517 lbs per cubic yard (307 kg per cubic meter). The weight of flyash used in the mix shall not be less than 15% nor more than 25% when determined by dividing the weight of flyash by the combined weight of flyash and portland cement.

2.1.3. Coarse Aggregates: Aggregates shall comply with the quality requirements of ASTM C -33. The grading requirements for coarse aggregates of ASTM C 33 do not apply. Aggregates shall be combined to produce an aggregate grading which satisfies the grading criteria of the approved mixture proportioning study. Crushed portland cement concrete may be used as an aggregate when the specified quality requirements are satisfied. Coarse aggregate is defined as that material retained on and above the Number 4 ASTM Standard Sieve (#4 sieve) size.

2.1.3.1. Composition: Coarse aggregate shall be washed and shall consist of gravel, crushed gravel, crushed stone, or a combination thereof.

2.1.3.2. Quality: Coarse aggregates, as delivered to stockpiles for use in the project, shall consist of washed clean particles, which satisfy one half the listed limits for deleterious substances and physical property requirements of ASTM C-33, Table 3.

2.1.3.3. Particle Shape: Particle shape of the coarse aggregate shall be generally rounded if gravel and cubical in shape if crushed. The quantity of flat and elongated particles in any size group shall not exceed 20 percent, by weight, as determined by CRD-C-119. A flat particle is defined as one with a ratio of width to thickness greater than three. An elongated particle is one having a ratio of length to width greater than three.

2.1.3.4. Size and Grading: The nominal maximum aggregate size shall be 1.5 inch, Class designation 4M as defined in ASTM C-33.

2.1.4. Blending Sizes: Blending sizes are defined as intermediate size particles nominally passing the 9.5 mm sieve and retained above the ASTM Number 50 Standard Sieve (#50 sieve) size.

2.1.4.1. Composition: Blending sizes shall be washed clean materials of either natural deposits, manufactured products, or combinations thereof.

2.1.4.2. Quality: Blending sizes shall meet the limits of deleterious substances and/or physical property requirements of ASTM C 33 based upon the aggregate sizes. Material which is of the coarse material size, by definition, shall meet coarse aggregate quality requirements. The material portion which meets the definition of the fine aggregate shall meet the quality requirements of the fine aggregate.

2.1.4.3. Particle Shape: The particles shall be generally cubical in shape without the presence of elongated or slivered materials.

2.1.5. Fine Aggregate: Fine aggregate is defined as clean granular material which passes an ASTM Number 4 Standard Sieve (#4 sieve) size.

2.1.5.1. Composition: Fine aggregate shall be natural sand(s), or, a blend of mechanical (manufactured) sand and natural sand(s).

2.1.5.2. Quality: The limits for deleterious substances in the fine aggregate shall not exceed those given in ASTM C 33, Table 1.

2.1.5.3. Grading: The fine aggregate, as delivered to the stockpile, should be proportional to the limits of ASTM C 33 and geometrically similiar to the lower limit grading curve. The maximum limitation of the fineness modulus of 3.1 specified in ASTM C-33 is not applicable and may be exceeded. The fineness modulus shall not be less than 2.3.

2.1.6. Water: Water for washing aggregates and for mixing concrete shall be fresh and free from injurious amounts of oils, acid, salt, alkali, organic matter, and/or other deleterious substances. The properties of the water shall exceed the minimum requirements given in CRD C-400.

2.2. MIXTURE PROPORTIONS: The concrete mixture proportions shall be determined by the contractor QC LAB. The proportioning shall be accomplished such that workability, finish, and strength are achieved. Durability requirements will be assumed to be satisfied when the mixture is proportioned as a well-graded combined aggregate and the range for air content and specified water-cement ratio are satisfied. Workability shall be judged by the contractor, giving consideration to the intended method of placement. An individual mixture proportion shall be developed for each expected method of concrete placement, i.e., slipform, fixed form, or hand placement.

2.2.1. Composition: Concrete composition shall be Portland cement, water, aggregates, and air entraining admixtures. Other chemical or mineral admixtures may be used at the option of the contractor.

2.2.2. Control of the Mixture: The contractor is expected to adjust the mixture proportions, as necessary, to maintain the workability depending on the construction environment. The contractor shall inform the Contracting Officer of any changes to the mixture proportions after the performance of the test strip construction.

2.2.3. Combined Aggregate Grading:

2.2.3.1. Aggregate Grading Controls : The coarse aggregate, blending sizes (when required), and fine aggregate shall be combined to be graded from the coarse to the fine. Reports of grading shall include sieve sizes 50 mm, 37.5 mm, 25 mm, 19 mm, 12.5 mm, 9.5 mm, No.4, No. 8, No. 16, No. 30, No. 50, and No. 100.

2.2.3.2. Percent Aggregate Retained Graph: The combined grading shall be plotted on a graph as the percentage retained for each reporting sieve size versus the considered sieve size. The Y-axis is the percent retained. The X-axis is the sieve size. The plot of the graph should be a smooth curve showing a transition between coarse and fine aggregate. The plot shall not have a significant valley or peak between the 9.5 mm size and the finest reporting sieve size. Interpretation of the grading requirement and examples of the presentation is given in US Air Force publication Proportioning Concrete Mixtures with Graded Aggregates, A Handbook for Rigid Airfield Pavements.

2.2.3.3. Coarseness Factor/Workability Factor: The combined gradation shall be used to calculate a coarseness factor and a workability factor.

2.2.3.3.1. The coarseness factor is defined as the percent of combined aggregate retained on the No. 8 sieve, which is also retained on the 9.5 mm sieve. It is calculated by dividing the percent of material retained above the 9.5 mm sieve by the percent retained above the No. 8 sieve, times 100.

2.2.3.3.2. The workability factor is defined as the percentage of combined aggregate passing the No. 8 sieve. The workability factor is adjusted by 2.5 units for each 72.5 lbs per cubic yard (43 kg per cubic meter) of cementious material above 565 lbs per cubic yard (335 kg per cubic meter). If the total cementious material is 565 lbs per cubic yard (335 kg per cubic meter) there is no adjustment. Adjusted Workability Factor : [((Weight of Mix-565)/72.5)*2.5]+Workability Factor.

2.2.3.3.3. The factors, defined above, shall be plotted on a chart similar to Figure 2.2.3. The coarseness factor shall not be greater than 80 nor less than 30. The plot of the workability factor and the coarseness factor shall be a single point above the control line. The plot shall not be below the control line. The aggregate grading shall be selected to allow for a variance in the stockpile grading.

Figure 2.2.3 - Aggregate Proportioning Guide

2.2.4. Cementious Materials Content: The minimum cementious materials content shall be 565 lbs per cubic yard (335 kg per cubic meter) of concrete.

2.2.5. Water Cementious Materials Ratio: The weight of water to weight of cementious materials ratio shall not exceed a value of 0.45.

2.2.6. Air Content: The air content, by volume, shall be 6 per cent. The mix proportioning study shall allow for air loss, or gain, because of mixing, transporting, placement, temperature, and finishing. The air content for acceptance will be measured from concrete samples selected from in front of the paver. Appropriate adjustments for the air content at discharge from the mixer shall be included in the proportioning studies.

2.2.7. Concrete Strength: The concrete shall be proportioned for a minimum flexural strength of 650 psi (4.5 Mpa) at 90 days of age determined using the procedures of ASTM C 78. The proportioning study shall be provided in report format and will include a graph of the flexural strength versus time (in days) for the selected mixture proportions. Concrete specimens shall be tested at the ages of 7, 14, 28 and 90 days, minimum. The 90-day test criteria will be waived when the 28-day strength exceeds 90% of the strength specified.

2.2.8. Optional Concrete Strength Determination: The contractor may elect to develop a correlation between the flexural strength and the compressive strength of the concrete. If the option is selected, the compressive strength criteria may be used in lieu of flexural strength for concrete testing. The compressive strength correlation shall be developed for each mixture to be used for the work. A total of fifteen (15) sets of companion compressive cylinder specimens shall be made for the correlation from the first fifteen sets of beams cast in the field. Minimum frequency for flexural testing is described in paragraph 3.12.4.1STRENGTH TESTS CONTRACTOR QUALITY CONTROL, in Part 3 of this specification.

2.2.9. Concrete Mixture Proportions Adjustments: The contractor shall adjust field batch proportions to conform to the approved mixture proportioning study and when necessary to adapt to environmental changes which vary the placement conditions.

2.3. OTHER MATERIALS:

2.3.1. Reinforcement and Tie Bars: All materials used for reinforcement or tie bars shall be free from loose flakey rust, loose scale, oil, grease, mud, or other deleterious materials which would reduce the bond with the concrete.

2.3.1.1. Bar mats shall conform to ASTM A 184. Welded wire fabric shall conform to ASTM A 185.

2.3.1.2. Tie bars shall be deformed steel bars conforming to ASTM A 615, A 616, or A 617 with sizes and lengths indicated on the drawings.

2.3.2. Dowel Bars: Dowels shall be smooth steel bars 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 1 mm on the diameter of the dowel and does not extend more than 1 mm from the end of the dowel. Dowels shall be epoxy coated steel bars, or painted on all surfaces with one coat of paint meeting Federal Spec TT-P-664. Dowel bars shall conform to ASTM A 615, grade 40 or 60; ASTM A 616, grade 50 or 60; or ASTM A 617, grade 40 or 60.

2.3.3. Epoxy Resin: All epoxy resin materials shall be two component materials conforming to the specification of ASTM C-881, Type III or Type V.

2.3.3.1. The materials used for bonding freshly mixed Portland concrete to hardened concrete shall be Type V materials.

2.3.3.2. The materials used for patching of spalls or other minor surface voids and for use for embedding dowels shall be Type III. The grade used for embedding dowels shall be Grade 3.

2.3.4. Joint Filler for Expansion Joints: Filler shall be preformed materials conforming to ASTM D 1751 or ASTM D 1752.

2.3.5. Curing Materials: Membrane forming curing compounds shall be Type 2, Class A, meeting the ASTM C 309-94 requirements.

END OF PART 2 - PRODUCTS AND MATERIALS

3. PART 3 - EXECUTION

3.1. PRODUCTION OF CONCRETE:

3.1.1. Location of Plant: The drawings will identify the location of the mixing plant, the stockpile areas, and egress when the mixing plant can be located on Government property.

3.1.2. Batching Plant: The batching plant will produce a mixture which is uniform and consistent. The batching plant will have the capacity to produce a steady and consistent supply to the paver. The capacity of the batching plant shall be consistent with the placement capacity.

3.1.2.1. Equipment: The batching controls shall be either semiautomatic or automatic. Separate bins or compartments shall be provided for each size group of aggregate and for cementitious materials. If measured by weight, water shall not be weighed cumulatively with another ingredient, and filling and discharging valves shall be interlocked so that the discharge valve cannot be opened before the filling valve is closed. An accurate mechanical device for measuring and dispensing each admixture shall be provided.

3.1.2.2. Scales: Scales shall be provided for the accurate measurement and control of each of the materials in each batch of concrete. 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.

3.1.2.3. Moisture Control: The plant shall be capable of adjustment to compensate for moisture contents variations within aggregate stockpiles.

3.1.3. Concrete Mixers:

3.1.3.1. General: The mixer(s) shall not be charged in excess of the capacity recommended by the manufacturer. The mixer drum(s) shall be kept free of hardened concrete.

3.1.3.2. Mixers: Mixers shall be provided with an acceptable device to lock the discharge mechanism until the required mixing time has elapsed.

3.1.3.3. Mixing Time and Uniformity: The mixing time for each batch, after all solid materials are in the mixer, will be determined using CRD-C 55 procedures. The mixer discharge product shall meet the requirements of TABLE 3.1.3. Mixer uniformity shall be determined prior to start of concrete mixing and placement by the contractor QC LAB.

TABLE 3.1.3

UNIFORMITY TOLERANCES IN CONCRETE MIXERS

Parameters Tested For

Maximum permissible range in results of Tests and

Samples taken from three locations in the concrete batch.

Weight per cubic meter of mortars

1.0 calculated to an air-free basis, kg per cubic meter

Air content, volume percent of concrete

Coarse aggregate content, portion

6.0 by weight of each sample retained on No. 4 sieve, percent

Average compressive strength at 7

10.0 days for each sample based on average strength of all test specimens, percent

Water content, portion by weight of each sample passing No. 4 sieve, percent

3.2. TRANSPORTING EQUIPMENT: Concrete shall be transported to the point of discharge without segregation. Concrete may be placed directly in front of the paver by the transport vehicle provided the vehicle can traffic the base surface without causing rutting or deformation of the surface. The surface on which the pavement is being placed shall be maintained free from foreign materials and concrete that has begun to harden.

3.3. PLACING:

3.3.1. General: Concrete shall be placed within 45 minutes from the time water and cement are charged into the mixing drum. Concrete shall be deposited as close as possible to its final position. The placement of the concrete shall be uniform and continuous. Workmen with foreign material on their footwear, or construction equipment that might deposit foreign material, shall not be permitted in the placed concrete mixture.

3.3.2. Equipment: Mechanical pavers shall be self-propelled and shall be capable of consolidating and shaping the plastic concrete to the desired cross section in one forward pass. The paver shall finish the surface, and free edges, so that hand finishing is minimal. The paver shall have sufficient weight and power to handle the amount of concrete required for the full-lane width and depth without drag or distortion of the paver components. The paver shall be equipped with vibrators automatically controlled so that the vibrators stop as motion ceases.

3.3.3. Spreading: Spreading shall be by machine method except when transporting equipment is permitted on the placement surface. 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. Hand spreading shall be done with shovels; rakes are not allowed. Machines that cause displacement of forms or rut the prepared placement surface shall not be used on the project.

3.3.4. Vibration: Concrete shall be consolidated with mechanical vibrating equipment. The number of vibrator units and the power of each shall be adequate to properly consolidate the concrete. The vibrating unit shall be mounted on a frame with controls which allow operation at any desired depth including withdrawal. Vibrators shall not be used to spread the concrete.

3.3.5. Placing Reinforcing Steel:

3.3.5.1. Pavement Thickness Greater Than 12”: Reinforcement steel shall be installed by pressing it into plastic concrete which has been deposited on the underlying material, consolidated, and struck to an elevation slightly higher than the design elevation of the steel reinforcement. A cover layer of concrete will be placed and consolidated within 30 minutes of the initial layer being placed.

3.3.5.2. Pavement Thickness Less Than 12”: Reinforcement steel shall be positioned on suitable chairs before concrete placement.

3.3.6. Placing During Inclement Weather: The Contractor shall submit to the Contracting Officer a plan which describes the procedures for placement, finishing, curing, and protection of concrete during periods of inclement weather.

3.3.6.1. Placing During Cold Weather: Concrete placement shall be discontinued when the ambient air temperature reaches 40 degrees F and is falling. Placement may begin when the ambient air temperature, and the placement surface, is at 35 degrees F and is rising. Provision shall be made to protect the concrete from freezing during the curing period. Concrete damaged by freezing shall be removed and replaced as specified in paragraph3.10 REMOVAL AND REPLACEMENT OF DEFECTIVE CONCRETE.

3.3.6.2. Placing During Hot Weather: When the hot weather concreting procedures are likely to apply, forms and the underlying material shall be sprinkled with water immediately before placing the concrete. Concrete shall be placed at the coolest temperature practicable,but in no case shall the temperature of the concrete, when placed, exceed 90 degrees F.

3.4. FINISHING: Finishing operations shall be started immediately after placement of the concrete. Hand methods of finishing are permitted only on odd shapes and in the event of breakdown of the mechanical equipment. Finishing equipment and tools shall be clean and in good condition.

3.4.1. Equipment: The finishing machines shall operate at a continuous and uniform motion without dragging or distortion.

3.4.1.1. Transverse Finishing: Directly after placement, concrete shall be struck off and screeded to the crown and cross section of the design drawings. Water shall not be put on the surface of the concrete to facilitate finishing operations. Excessive manipulation that builds mortar and water on the surface are not permitted.

3.4.1.2. Mechanical Floating: After completion of screeding, a mechanical float may be operated to smooth and finish the pavement. The float shall be operated so as to maintain contact with the surface at all times. Components of mechanical devices which are used to float and finish the pavement surface shall have provision to disperse water and slurry buildup.

3.4.2. Finishing After Slipform Paving: The slipform paver shall finish the surface and the paving lane edges as the equipment maintains forward motion. The finishing equipment shall be limited to the paver screed and a float. Floating may be accomplished by hand and by mechanical bull floating. Under no circumstances shall concrete slurry be accumulated on the surface of the finished concrete nor shall concrete slurry be permitted to run down the vertical edges of the placed pavement. Concrete slurry shall not be used to build up along the edges of the concrete to compensate for excessive edge slump.

3.4.3. Hand Finishing (Odd Shaped Slabs and Equipment Breakdown):

3.4.3.1. Equipment: A straightedge and a longitudinal float shall be provided. The handle for each shall be longer than one-half the width of pavement being finished. The longitudinal float shall be at least 3 meters long, of rigid design and construction, and substantially braced as to maintain a plane surface.

3.4.3.2. Finishing and Floating: As soon as placed and vibrated, the concrete shall be struck off, screeded to the crown and cross section detailed, and the entire surface floated.

3.4.4. Surface Correction and Testing: After finishing is completed but while the concrete is still plastic, minor irregularities and score marks in the pavement surface shall be eliminated by using straightedges. Straightedges shall be 4 meters in length (minimum) and shall be operated from the sides of the pavement or from bridges. A straightedge operated from the side of the pavement shall be equipped with a handle longer than one-half the width of the pavement. The surface shall then be tested for trueness with a straightedge held in successive positions parallel and at right angles to the center line of the pavement as necessary to detect variations.

3.4.5. Texturing: A texture shall be applied after the surface sheen (bleed water) disappears and prior to initial set. Hand texturing using the specified devices is allowed for irregular or odd shaped slabs.

3.4.5.1. Burlap-Drag Texture: Surface texture shall be applied by dragging the surface of the pavement, in the direction of the concrete placement, with an approved multiple-ply burlap drag at least 3 feet in width and equal in length to the width of paving. The leading edge of the burlap shall be cleaned and changed as required. The dragging shall be done so as to produce a uniform surface texture without disfiguring marks.

3.4.5.2. Broom Texturing: Surface texture shall be applied using an approved hand or mechanical stiff bristle broom of a type that will produce uniform corrugations. For hand brooming, the brooms shall have handles longer than half the width of slab to be finished. The hand brooms shall be drawn transversely across the surface from the center line to each edge with slight overlapping strokes. For mechanical operations, the broom shall be operated with the width of the broom parallel to the pavement center line. The broom shall be capable of traversing the full width of the pavement in a single pass at a uniform speed and with a uniform pressure. Successive passes of the broom shall be overlapped the minimum necessary to obtain a uniformly textured surface. Brooms shall be washed thoroughly and dried at frequent intervals during use. Brooming should be completed before the concrete surface will be unduly torn or roughened, but after mortar will not flow and attenuate the texture.

3.4.5.3. Artificial Turf Texturing: Surface texture shall be applied by dragging the surface of the pavement in the direction of concrete placement with a full-width drag made with artificial turf. The leading transverse edge of the artificial turf drag will be securely fastened to a lightweight pole on a traveling bridge. At least 600 mm of the artificial turf shall be in contact with the concrete surface during dragging operations. The turf drag shall be maintained free of cement or aggregate build-up and shall not result in dislodging of aggregates from the surface.

3.4.6. Outlets in Pavement: Recesses for tie-down anchors, lighting fixtures, and other outlets in the pavement shall conform to the details and dimensions given in the drawings.

3.5. FORM REMOVAL: Forms shall remain in place at least 12 hours after the concrete has been placed. When conditions are such that the strength gain of the concrete is delayed, the forms shall be left in place for a longer period. Forms shall be removed without injuring the concrete. Bars or heavy tools shall not be used to pry against the concrete while removing the forms.

3.6. CURING:

3.6.1. General: Concrete shall be protected against loss of moisture for at least 7 days from the time of concrete placement. Plastic concrete shall be protected from rain and flowing water.

3.6.2. Membrane Curing: A uniform coating of white-pigmented membrane-curing compound shall be applied to the surface of the concrete as soon as the free water (bleed water) disappears and after texturing is done. Formed surfaces shall be coated immediately after the forms are removed. Curing compound will be re-applied to concrete surfaces subjected to rainfall which occurs within 3 hours after the initial application. Concrete surfaces to which membrane-curing compounds have been applied shall be protected during the entire curing period from pedestrian and vehicular traffic except as required for joint-sawing operations and surface smoothness tests.

3.6.2.1. Machine Application: The curing compound shall be applied to the finished surfaces using an automatic spraying machine. The machine shall be self-propelled and shall straddle the paved lane. The machine shall have spraying nozzles that can be controlled to cover the pavement surface with a uniform application of curing compound. The drum used for supply to the spray nozzles shall be continuously agitated mechanically for the full depth of the drum during the application. Spray equipment shall have a wind guard. The curing compound shall be applied with an overlapping coverage in two-coats. The total coverage shall not be more than 5 sq meter per liter of curing compound.

3.6.2.2. Hand Application: Hand-operated pressure sprayers will be permitted only on odd widths or on concrete surfaces exposed by the removal of forms. When the application is made by hand-operated sprayers, the second coat shall be applied in a direction at right angles to the direction of the first coat

3.7. JOINTS:

3.7.1. General: Joints will be constructed to the details of the drawings. All joints shall be perpendicular to the finished grade of the pavement. Transverse expansion and contraction joints shall be straight and continuous from edge to edge of the pavement.

3.7.2. Longitudinal Construction Joints: Dowel bars shall be installed in longitudinal construction joints except where thickened edge construction and an expansion joint is required. Tie bars will be installed at locations indicated on the drawings. Dowels and tie bars shall be installed in conformance with paragraph 3.8DOWELS AND TIE BARS, below.

3.7.3. Transverse Construction Joints: Transverse construction joints shall be installed at the end of each day's placing operations and at any other location when concrete placement is interrupted for more than 45 minutes. These joints shall be located at a planned joint, except in case of equipment breakdown. When concrete placement cannot be continued, the transverse construction joint may be installed within a planned slab unit but not less than 10’ (3 meters) from a planned transverse joint. Dowels shall be installed in transverse construction joints.

3.7.4. Expansion Joints: Expansion joints shall be formed by placing a preformed filler material at a construction joint. Expansion joints shall be formed around features that project through, into, or against the pavement.

3.7.5. Contraction Joints: Transverse, and longitudinal, contraction joints shall be of the weakened-plane or dummy type formed by sawing a groove in the hardened concrete with a power-driven sawblade. The depth of the groove formed by sawing shall be one fourth of the concrete thickness or deeper.

3.7.5.1. Sawed Joints: Sawed joints shall be constructed by sawing a groove in the concrete. The time of sawing shall vary but shall be done before uncontrolled shrinkage cracking occurs. Sawing of the joints shall commence as soon as the concrete has hardened sufficiently to permit cutting the concrete without chipping, spalling, or tearing. The sawed faces of joints shall be inspected for undercutting or washing of the concrete caused by early sawing. The saw cut shall not vary more than ½” (12 mm) from planned joint alignment.