Section_C_Attach_2_HartBarConcrete_Spec.docx

PART 1: GENERAL

1.01 SUMMARY:

A. Section Includes: The excavation of material, including the excavation for concrete vault toilet structures, dewatering, placing backfill, the disposal of excavated materials, construction of structural backfill, and construction of parking lot subgrades.

B. Related Sections:

1.02 SUBMITTALS:

A. General: Submittals shall be according to Section 01009 - General Information and Requirements.

1.03 PROJECT/SITE CONDITIONS:

A. Structural backfill materials shall be supplied from approved soil material which has been excavated from the work location and/or from a designated borrow source.

1.04 QUALITY ASSURANCE:

A. Construction Tolerances: Maximum allowable deviation from construction stakes and drawings shall be as follows:

B. Causes for Rejection: Materials and compaction may be rejected for, but not limited to, the following reasons:

1. Failure to supply certifications or submittals to the Contracting Officer Representative.

2. Certified tester absent from site during required compaction.

3. Compacting backfill in lifts greater than 12-inches.

4. Using unclassified backfill material which has not been tested and/or approved.

5. Construction tolerances not met.

PART 2: PRODUCTS

2.01 MATERIALS:

A. 1 ½” crushed aggregate foundation fill. Refer to Section 02233 Aggregate Surfacing.

PART 3: EXECUTION

3.01 PREPARATION:

A. Clearing: Refer to Section 02111 Clearing and Grubbing.

B. Install petroleum containment booms and erosion control materials prior to performing work.

C. The contractor shall stake the excavation/fill limits prior to beginning excavation.

D. The area to be excavated, and the surface area to be covered by fill material, shall be thoroughly cleared and stripped of vegetative matter, brush, trees, stumps, roots, loose rocks, and other objectionable materials.

3.02 INSTALLATION:

A. Concrete Slab Preparation:

Excavation for the slab shall be to the depth and dimensions shown in the plans. Clean the excavated surface of loose and/or disintegrated material before fill material is placed.

B. Backfilling and Compaction:

1. Subgrade reinforcement: Construct fill to dimensions shown on the drawings. Backfill shall be placed in horizontal layers not exceeding 12” in depth. Use compression-type rollers at speeds less than 6 feet per second and vibratory rollers at speeds less than 3 feet per second. Compact each layer of material full width with one of the following and until there is no visible evidence of further consolidation.

a. Four roller passes of a vibratory roller having a minimum dynamic force of 40,000 pounds impact per vibration and a minimum frequency of 1000 vibrations per minute.

b. Eight roller passes of a 20-ton compression-type roller.

c. Eight roller passes of a vibratory roller having a minimum dynamic force of 30,000 pounds impact per vibration and a minimum frequency of 1000 vibrations per minute.

2. This method of backfilling and compaction shall be continued until the required subgrade elevation has been reached.

3.03 DISPOSAL:

Requirements: Contractor shall be responsible to dispose of excess excavated and unsuitable material. Items or debris not designated as salvage for the government shall become the property of the contractor. The contractor shall be responsible for disposal of materials in a legal manner and for payment of any fees required. Sale of material onsite is not allowed unless authorized in writing by the Contracting Officer Representative. When hazardous materials are encountered during operations, the contractor shall comply with applicable federal, state, and local regulations, laws, and ordinances concerning removal, handling, and protection against exposure or environmental pollution.

PART 4: MEASUREMENT AND PAYMENT

4.01 METHOD OF MEASUREMENT:

Units: The work described in this section will be measured and paid for on a lump sum basis.

4.02 BASIS OF PAYMENT:

No direct payment for the work described under this section will be made. The contractor shall include consideration for this item in the price for other items of the contract.

END OF SECTION

02224-2

PART 1: GENERAL

0. SUMMARY:

1. Section Includes: Furnishing and placement of form work, reinforcement steel, and placement and curing of ready-mix concrete for concrete slabs on grade.

1. Related Sections:

0. REFERENCES:

1. American Concrete Institute:

1. American Society for Testing and Materials:

1. Concrete Reinforcing Steel Institute:

Placing Reinforcing Bars, CRSI, 9th Edition

0. SUBMITTALS:

1. General: Submittals shall be according to Section 01009 - General Information and Requirements.

1. Certificates of Conformance: Submit one copy of written certification from the supplier of the following Contractor-furnished items to be used on this project that they conform to the requirements of this specification section.

1. Portland Cement

1. Aggregate

1. Reinforcing Steel

1. Mix Design: Submit one copy of the design mix and strength, class and type of concrete to be used on this project. Mix design and strength tests results shall be prepared by a certified testing laboratory.

0. QUALITY ASSURANCE:

1. Provide Contracting Officer Representative a delivery ticket in accordance with ASTM C-94 for each load of concrete.

1. Causes for Rejection: Concrete may be rejected for, but not limited to, the following reasons:

1. Excessive or inadequate slump and/or other excessive variation from the approved mix design.

1. Failure to immediately cover or seal concrete during initial 7-day curing period.

1. Inadequate strength after 28 days as indicated by test cylinders. The Contractor shall be responsible for further testing required by the Government to determine the strength of the concrete.

PART 2: PRODUCTS

0. MATERIALS:

1. Cement: Portland cement, Type I, II or IIA, according to ASTM C 150, Use one brand of cement.

1. Water: Potable water shall be used for mixing concrete.

1. Aggregates: The aggregate shall be hard, durable, uncoated rock according to ASTM C 33.

1. The coarse aggregate shall have a maximum size of 1 inch, and not over 5% passing the No. 4 sieve.

1. The fine aggregate shall completely pass the No. 4 sieve with no more than 5% passing the No. 100 sieve. The fine aggregate shall contain no silt, loam, clay or organic particles.

1. Reinforcing Steel: Shall be deformed bars, shall have a minimum yield of (60) ksi, and shall conform to grade (60) of ASTM A 615. The size of the bars shall be as indicated on the drawings.

1. Reinforcement Supports: Shall be of the size and type called for by the CRSI and shall be arranged, spaced, and tied as called for by those requirements.

0. READY-MIXED CONCRETE:

1. Requirements: Ready-mixed concrete shall be according to ASTM C 94 and be designed for a 28-day compressive strength of 3000 psi. Slump shall be 2 to 4 inches as determined by ASTM C 143. The entrained air range shall be 4% to 6%. Loads may be applied to the concrete after it has reached a compressive strength of 2500 psi. If super plasticizers are used in the concrete, the slump may be a maximum of 11inches.

1. Water reducing admixtures and super plasticizers may be used when approved by the Contracting Officer Representative. The time when concrete discharge must be completed due to retardant used shall be indicated on the batch ticket. Use a quantity of an admixture within the manufacture’s recommendations.

1. Discharge of non-retarded concrete shall be completed within 11/2 hours after the introduction of cement into the aggregate. The time interval between placement of batches shall not exceed 30 minutes.

1. The maximum water/cement ratio (per pound) shall be 0.40.

PART 3: EXECUTION

0. PREPARATION:

1. Foundation Preparation for Slabs: Subgrade or base material shall be level, uniformly graded and well compacted.

1. Form Construction: Construct forms to the sizes, shapes, lines, and dimensions shown on the drawings to obtain accurate alignment, location, grades, and level and plumb surfaces in finished structures. The Contractor shall provide construction aids and embedded items such as anchor bolts. Fabricate forms for easy removal without hammering or prying against the concrete surfaces. Provide crush plates or wrecking plates if stripping may damage the concrete. Form oil may be applied to facilitate removal of forms. Forms and subbase shall be wet before placement of concrete.

1. Form Inspection: Notify the Contracting Officer Representative 24 hours in advance of concrete placement to allow for inspection of forming and placement of items embedded in the concrete. Excess water shall be removed from the forms before concrete placement.

1. Reinforcing Steel: Shall be held securely in position by new rust free steel wire, mortar blocks, or metal chairs during the placement of concrete. Reinforcement shall be inspected by the Contracting Officer Representative before concrete is placed.

0. CONCRETE PLACEMENT:

1. Placement and Consolidation: Each lift shall be adequately vibrated, rodded, or spaded into place to fill voids. Where more than one lift is placed, a vibrator shall be used to consolidate the concrete by penetrating through the upper lift and at least 6 inches into the lower lift. Vibrators shall not be used next to the form or to move concrete. Concrete shall be deposited as nearly as practical to its final position to avoid flow-caused segregation of the aggregate. Concrete shall not be dropped more than five feet vertically. A pump or other Contracting Officer Representative approved method shall be used to place concrete more than five feet vertically.

1. Bonding to Existing Concrete: When a bond is desired between a fresh pour of concrete and concrete that has set, the surface of the in-place concrete shall be thoroughly cleaned of loose material, and the in-place concrete soaked with water.

1. Concrete Placement Under Adverse Conditions: During hot weather, refer to ACI 305R. During cold weather, refer to ACI 306R. Materials required for protection shall be on the jobsite before concrete work is started. Do not place concrete on a frozen subgrade or against surfaces having deposits of frost, snow, or ice.

1. Contractor shall have a backup vibratory device that is in working order and available onsite during all concrete pours.

0. CONCRETE FINISHING:

1. Concrete Slabs Surface Finish: Screed, float and trowel exposed surfaces for a uniform, smooth, dense finish. Texture finished surfaces with a light broom and tool edges.

1. Form Removal: Form work not supporting concrete may be removed after curing at not less than 50 degrees Fahrenheit for 48 hours after placing the concrete, and when curing and protection procedures are followed as specified. The concrete should be sufficiently hard so as not to be damaged by form removal.

1. Concrete Finish Patching: Immediately after form removal, remove minor bulges and projections on exposed concrete by chipping or tooling, and rubbing or grinding the surface. Remove honeycombed and other defective areas to sound concrete with right angle edge surfaces. Brush cavities with a grout of cement and water, and point with Portland Cement Mortar. Cure repairs the same as the concrete.

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

B. Revise criteria for locating construction joints in "Construction Joints" Paragraph below to suit Project.

Construction Joints: Install so strength and appearance of concrete are not impaired, at locations indicated on Drawings.

C. Insert spacing of contraction (control) joints here or on Drawings if required. Contraction-joint spacings vary with slab thickness, aggregate size, and slump based on PCA's recommendations. Depth of joint may be varied to suit cutting method or if steel-fiber reinforcement is used.

Contraction Joints in Slabs-on-Grade: Form weakened-plane contraction joints, sectioning concrete into areas as indicated. Construct contraction joints for a depth equal to at least one-fourth of concrete thickness as follows:

Retain type of joint-forming method from "Grooved Joints" and "Sawed Joints" subparagraphs below or retain both subparagraphs as Contractor's option. Insert joint spacing if not indicated on Drawings.

Grooved Joints: Form contraction joints after initial floating by grooving and finishing each edge of joint to a radius of 1/8”. Repeat grooving of contraction joints after applying surface finishes. Eliminate groove tool marks on concrete surfaces.

Retain "Sawed Joints" Subparagraph below if saw cutting is permitted. Description does not distinguish conventional wet- and dry-cut saws from early-entry dry-cut saws. Timing is critical to sawed joints. Early-entry dry-cut saws are used within one to two hours of finishing concrete. To leave concrete undamaged from sawing, conventional saw cutting must be delayed, usually 4 to 12 hours, but not so long that uncontrolled cracking of concrete could occur.

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 does not tear, abrade, or otherwise damage surface and before concrete develops random contraction cracks.

D. Isolation Joints in Slabs-on-Grade: After removing formwork, install joint-filler strips at slab junctions with vertical surfaces, such as column pedestals, foundation walls, grade beams, and other locations, as indicated.

0. CONCRETE CURING:

1. Curing Time: Cure concrete for a period of seven consecutive days from time of placement. Use one of the following methods:

1. Liquid membrane forming compound shall be sprayed on and shall be dry to touch in not more than four hours from time of application according to paragraph 7.1 ASTM C 309.

1. Cover the damp concrete surfaces with impermeable sheets of polyethylene material or other sheet coverings with joints lapped and sealed to retain moisture.

1. Concrete forms may be left in place to provide proper curing of concrete in contact with forms. Curing of unformed concrete surfaces shall be by one of the methods described above, and shall begin as soon as the concrete has hardened enough to allow application of the curing material. If forms are removed before the end of the 7-day period, curing by use of the liquid membrane forming compound or sheets of polyethylene material shall begin immediately and shall continue for the remainder of the 7-day curing period.

PART 4: MEASUREMENT AND PAYMENT

1. METHOD OF MEASUREMENT:

Units: The work described in this section will be measured and paid for on a lump sum basis.

1. BASIS OF PAYMENT:

No direct payment for the work described under this section will be made. The contractor shall include consideration for this item in the price for other items of the contract.

END SECTION