033000_Cast-in-place_concrete.pdf

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WATER SYSTEM CAST-IN-PLACE CONCRETE

SECTION 033000

CAST-IN-PLACE CONCRETE

PART 1 – GENERAL

1.1 SUMMARY

A. This Section includes cast-in-place concrete, including the use of synthetic fiber reinforcement in all concrete flatwork, concrete materials, mix design, placement procedures, and finishes.

B. See Division 31 Section "Structural Excavation and Backfill" for excavation and embankment for slabs-on-grade and Division 32 Section “Aggregate Base Courses” for aggregate fill under concrete.

1.2 SUBMITTALS

A. Product Data: For each manufactured material and product indicated.

B. Design Mixes: For each concrete mix indicated. Include Set Retarder Data if required.

C. Shop Drawings: Include details of steel reinforcement placement including material, grade, bar schedules, stirrup spacing, bent bar diagrams, arrangement, and supports.

D. Material certificates.

1.3 QUALITY ASSURANCE

A. See Division 1 Section “Quality Requirements” for reporting requirements.

B. Manufacturer Qualifications: A firm experienced in manufacturing ready-mixed concrete products complying with ASTM C 94 requirements for production facilities and equipment.

C. Comply with ACI 301, "Specification for Structural Concrete for Buildings", including the following, unless modified by the requirements of the Contract

Documents.

1. General requirements, including submittals, quality assurance, acceptance of structure, and protection of in-place concrete.

2. Formwork and form accessories.

3. Steel reinforcement and supports.

4. Concrete mixtures.

5. Handling, placing, and constructing concrete.

PART 2 – PRODUCTS

2.1 MATERIALS

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A. Formwork: Furnish formwork and form accessories according to ACI 301.

B. Reinforcement:

1. Reinforcing Bars: ASTM A 615, Grade 60, deformed.

2. Plain-Steel Wire: ASTM A 82, as drawn.

C. Concrete Materials:

1. Portland Cement: ASTM C 150, Type I or II.

2. Normal-Weight Aggregate: ASTM C 33, uniformly graded, coarse aggregate

No. 67 (3/4 inch to No. 4).

3. Lightweight Aggregate: ASTM C 330.

4. Water: Potable, complying with ASTM C 94.

5. Synthetic Fiber: Fibrillated or monofilament polypropylene fibers engineered and designed for use in concrete, complying with ASTM C 1116, Type III, ½ to

1-1/2 inches long.

D. Admixtures:

1. Air-Entraining Admixture: ASTM C 260.

2. Water-Reducing Admixture: ASTM C 494, Type A.

3. Water-Reducing and Accelerating Admixture: ASTM C 494, Type E.

4. Water-Reducing and Retarding Admixture: ASTM C 494, Type D.

5. Set Retarder: ASTM C 494, Type D.

E. Vapor Retarder: Multi-ply reinforced polyethylene sheet, ASTM E 1745, Class C, not less than 7.8 mils thick; or polyethylene sheet, ASTM D 4397, not less than 6 mils thick.

F. Joint-Filler Strips: ASTM D 1751, asphalt-saturated cellulosic fiber.

G. Curing Materials:

1. Evaporation Retarder: Waterborne, monomolecular film forming, manufactured for application to fresh concrete.

2. Absorptive Cover: AASHTO M 182, Class 2, burlap cloth made from jute or kenaf.

3. Moisture-Retaining Cover: ASTM C 171, polyethylene film or white burlap-polyethylene sheet.

4. Water: Potable.

5. Clear, waterborne, membrane-forming Curing Compound: ASTM C 309, Type 1, Class B.

2.2 CONCRETE MIXES

A. Comply with ACI 301 requirements for concrete mixtures.

B. Prepare design mixes, proportioned according to ACI 301, for normal-weight concrete determined by either laboratory trial mix or field test data bases, as follows:

1. Compressive Strength (28 Days): 4000 psi.

2. Slump: 4 inches.

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3. Water to Cement Ratio: <0.45

4. Add air-entraining admixture at manufacturer's prescribed rate to result in concrete at point of placement having an air content of 6.0 percent for concrete structures and slabs exposed to freezing and thawing, de-icer chemicals, or subjected to hydraulic pressure, and 4.5 percent for all other concrete, within a tolerance of plus 1.0 or minus 1.5 percent.

2.3 CONCRETE MIXING

A. Ready-Mixed Concrete: Comply with ASTM C 94 and ASTM C 1116.

1. When air temperature is between 85 and 90 deg F, reduce mixing and delivery time from 1-1/2 hours to 75 minutes; when air temperature is above 90 deg F, reduce mixing and delivery time to 60 minutes.

B. Project-Site Mixing: Measure, batch, and mix concrete materials and concrete according to ASTM C 94. Mix concrete materials in appropriate drum-type batch machine mixer.

1. For mixer capacity of 1 cu. yd. (0.76 cu. m) or smaller, continue mixing at least

1-1/2 minutes, but not more than 5 minutes after ingredients are in mixer, before any part of batch is released.

2. For mixer capacity larger than 1 cu. yd. (0.76 cu. m), increase mixing time by 15 seconds for each additional 1 cu. yd. (0.76 cu. m).

C. Provide batch ticket for each batch discharged and used in the Work, indicating

Project identification name and number, date, mix type, mix time, quantity, and amount of water added. Record approximate location of final deposit in structure.

PART 3 – EXECUTION

3.1 INSTALLATION, GENERAL

A. Formwork: Design, construct, erect, shore, brace, and maintain formwork according to ACI 301.

1. Variation from plumb lines and surfaces of column footings and walls shall not exceed 1/8 inch in 10 feet.

2. Variation in linear building lines from established position of columns, piers, or walls shall not exceed 1 inch in any bay of 20 feet or 1 inch in 40 feet or greater.

3. Variation in cross section dimension of footings and thickness of slabs and walls shall not exceed minus 1/4 inch or plus 1 inch.

B. Vapor Retarder: Install, protect, and repair vapor-retarder sheets according to

ASTM E 1643; place sheets in position with longest dimension parallel with direction of pour.

1. Lap joints 6 inches and seal with manufacturer's recommended tape.

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C. Steel Reinforcement: Comply with CRSI's "Manual of Standard Practice" for fabricating, placing, and supporting reinforcement.

1. Do not cut or puncture vapor retarder. Repair damage and reseal vapor retarder before placing concrete.

2. Except where shown otherwise on drawings, a minimum concrete coverage for steel reinforcement shall be as follows:

Minimum Cover

Cast against and permanently exposed to earth (footings). 3 inches

Exposed to earth or weather (foundation walls, etc.)

#6 through #18 bars 2 inches

#5 bars and smaller 2 inches

Not exposed to weather or in contact with the ground: (slabs, walls, joist).

#14 and #18 bars 2 inches

#11 and smaller 2 inches

Beams, girders, columns: Principal reinforcement, ties, stirrups, or spirals 2 inches

D. Joints: Construct joints true to line with faces perpendicular to surface plane of concrete.

1. Construction Joints: Locate and install so as not to impair strength or appearance of concrete, at locations indicated or as approved by CO.

2. Isolation Joints: Install joint-filler strips at junctions with slabs-on-grade and vertical surfaces, such as column pedestals, foundation walls, grade beams, and other locations, as indicated.

a. Extend joint fillers full width and depth of joint, terminating flush with finished concrete surface, unless otherwise indicated.

3. Contraction Joints in Slabs-on-Grade: Form weakened-plane contraction joints, spaced a maximum of 12 feet center to center. Construct contraction joints for a depth equal to at least one-fourth of the concrete thickness, as follows:

a. Grooved Joints: Form contraction joints after initial floating by grooving and finishing each edge of joint with groover tool to a radius of 1/8 inch.

Repeat grooving of contraction joints after applying surface finishes.

Eliminate groover marks on concrete surfaces, or

b. Sawed Joints: Form contraction joints with power saws equipped with shatterproof abrasive or diamond-rimmed blades. Cut 1/8-inch- wide joints into concrete when cutting action will not tear, abrade, or otherwise damage surface and before concrete develops random contraction cracks.

E. Tolerances: Comply with ACI 117, "Specifications for Tolerances for Concrete

Construction and Materials."

3.2 CONCRETE PLACEMENT

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A. Comply with recommendations in ACI 304R for measuring, mixing, transporting, and placing concrete.

B. Consolidate concrete with mechanical vibrating equipment.

C. Cold Weather Placing:

1. Protect concrete work from physical damage or reduced strength which could be caused by frost, freezing actions, or low temperatures, in compliance with ACI

306 and as herein specified.

2. When air temperature has fallen to or is expected to fall below 40oF, uniformly heat water and aggregates before mixing to obtain a concrete mixture temperature of not less 50oF, and not more than 80oF at point of placement.

3. Do not use frozen materials or materials containing ice or snow. Do not place concrete on frozen subgrade or subgrade containing frozen materials.

4. Do not use calcium chloride, salt or other materials containing antifreeze agents or chemical accelerators, unless otherwise accepted in mix designs.

D. Hot Weather Placing:

1. When hot weather conditions exist that would seriously impair quality and strength of concrete, place concrete in compliance with ACI 305 and as herein specified.

2. Cool ingredients before mixing to maintain concrete temperature at time of placement below 90oF.

3. Mixing water may be chilled, or chopped ice may be used to control temperature provided water equivalent of ice is calculated to total amount of mixing water.

3.3 FINISHING FORMED SURFACES

A. Rough-Formed Finish: As-cast concrete texture imparted by form-facing material with tie holes and defective areas repaired and patched, and fins and other projections exceeding 1/4 inch in height rubbed down or chipped off.

1. Apply to concrete surfaces not exposed to public view.

B. Smooth-Formed Finish: As-cast concrete texture imparted by form-facing material, arranged in an orderly and symmetrical manner with a minimum of seams. Repair and patch tie holes and defective areas. Completely remove fins and other projections.

1. Apply to concrete surfaces exposed to public view or to be covered with a coating or covering material applied directly to concrete, such as waterproofing or dampproofing.

C. Related Unformed Surfaces: At tops of walls, horizontal offsets, and similar unformed surfaces adjacent to formed surfaces, strike off smooth and finish with a texture matching adjacent formed surfaces. Continue final surface treatment of formed surfaces uniformly across adjacent unformed surfaces, unless otherwise indicated.

3.4 FINISHING UNFORMED SURFACES

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A. General: Comply with ACI 302.1R for screeding, restraightening, and finishing operations for concrete surfaces. Do not wet concrete surfaces.

B. Screed surfaces with a straightedge and strike off. Begin initial floating using bull floats or darbies to form a uniform and open-textured surface plane before excess moisture or bleed water appears on the surface.

1. Do not further disturb surfaces before starting finishing operations.

C. Nonslip Broom Finish: Apply a nonslip broom finish to surfaces indicated and to exterior concrete slabs. Immediately after float finishing, slightly roughen trafficked surface by brooming with fiber-bristle broom perpendicular to main traffic route.

3.5 CONCRETE PROTECTION AND CURING

A. General: Protect freshly placed concrete from premature drying and excessive cold or hot temperatures. Comply with ACI 306.1 for cold-weather protection, and follow recommendations in ACI 305R for hot-weather protection during curing. Set retarders are allowable as approved by the Contracting Officer. Follow all manufacturer’s instructions and specifications for set retarder use in concrete mix if required.

B. Evaporation Retarder: Apply evaporation retarder to concrete surfaces if hot, dry, or windy conditions occur before and during finishing operations. Apply according to manufacturer's written instructions after placing, screeding, and bull floating or darbying concrete, but before float finishing.

C. Begin curing after finishing concrete, but not before free water has disappeared from concrete surface.

D. Cure formed and unformed concrete for at least seven days as follows:

1. Moisture Curing: Keep surfaces continuously moist with absorptive cover, water saturated and kept continuously wet.

3.6 REMOVAL OF FORMS AND SHORES

A. The supporting forms and shoring shall not be removed until the members have acquired sufficient strength to support their weight and the loads superimposed thereon safely.

B. In no case may any forms or shoring be removed until the time and sequence has been approved by the CO.

C. Earlier removal than specified below may be approved by the CO, based on the weather and tests of job-cured cylinders.

D. All formwork shall be removed without damage to the concrete.

E. The minimum time for forms and shoring to remain in place shall be as follows:

1. Slabs on grade and sides of footings: 24 hours.

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F. Any request for earlier removal of forms and shoring shall be made to the CO in writing, along with supporting evidence that the safety of the structure will not be impaired.

G. Shoring shall be adequate in strength and shall be so designed and placed that the load from successive parts of the structure will be transmitted directly through the falsework without creating bending or shearing stresses in the concrete.

H. During the period that the forms are in place on the concrete work, keep wet at all times.

3.7 FIELD QUALITY CONTROL

A. Testing Agency: Contractor will engage a qualified independent testing and inspecting agency to sample materials, perform tests, and submit test reports during concrete placement. Tests will be performed according to ACI 301.

1. Testing Frequency: One composite sample for each day's pour of each concrete mix exceeding 5 cu. yd., but less than 25 cu. yd., plus one set for each additional

50 cu. yd. or fraction thereof.

2. Slump: Test slump of the concrete sample for each strength test and whenever consistency of concrete seems to vary, using ASTM C 143.

3. Test air content for each strength test in accordance with ASTM C 231, ASTM

C 173, or ASTM C 138.

4. Determine temperature of concrete sample for each strength test.

B. Batch Certification

1. A concrete batch certificate containing all items shown on the example in this section shall be completed and furnished to the CO with each load.

2. Concrete Batch Certification Form (page 03300-8) will be supplied by the

Forest Service or the contractor may use his own forms.

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U.S. DEPARTMENT OF AGRICULTURE

FOREST SERVICE

REGION 2

Concrete Batch Certification

Name of ready-mix batch plant

Serial Number of ticket Date Truck No.

Name of contractor

Name and location of job

Class of concrete

Amount of concrete

Time loaded Reading of revolution counter or time at first

Addition of water

Type and brand of cement

Amount of cement in batch

Water-cement ratio Total water added

Admixtures (amount and type)

Maximum size of aggregate

Weight of fine aggregate

Weight of coarse aggregate

I hereby certify that the above statements are true and correct.

Signature of ready-mix plant representative

Water added by receiver Initials

END OF SECTION