atch 1 2575 Spall Repair.pdf

Spall Repair of Concrete Pavements FA5000-12-R-0001 Attachment 1

2575- 1

1. SCOPE:

1.1 This section covers the repair of spalled Portland Cement concrete (PCC) areas using Type I or Type III concrete.

1.1 APPLICABLE STANDARDS:

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

1.1.2 American Society for Testing and Materials (ASTM) Standards

2.0 CONCRETE MIX DESIGN:

Pavements - REQ

FXSB 11-2102

Section 2575

Spall Repair of Concrete Pavements

C 31 Making and Curing Concrete Test Specimens in the Field

C 78 Flexural Strength of Concrete (Simple Beam With Third-Point Loading)

C 136 Sieve Analysis of Fine and Coarse Aggregates

C 143 Slump of Portland Cement Concrete

C 150 Portland Cement

C 171 Sheet Materials for Curing Concrete

C 173 Air Content of Freshly Mixed Concrete by Volumetric Method

C 192 Making and Curing Concrete Test Specimens in Laboratory

C 231 Air Content of Freshly Mixed Concrete by the Pressure Method

C 260 Air-Entraining Admixtures for Concrete

D 75 Sampling Aggregates

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2.1 Concrete Mix Design: The concrete mix design shall have a minimum compressive strength of 5,000 psi at 7 days of age, with an air content by volume of 5.5 percent, plus or minus 1-1/2 percent and max slump of 2".

3. EQUIPMENT; APPROVAL AND MAINTENANCE:

3.1 Dependable and sufficient equipment that is appropriate and adequate to accomplish the work specified shall be assembled at the site of the work a sufficient time before the start of paving to permit thorough inspection, calibration of weighing and measuring devices, adjustment of parts, and the making of any repairs that may be required. The equipment shall be maintained in good working condition.

4. SAMPLING AND TESTING OF MATERIALS:

4.1 Sampling and testing shall be performed by an approved commercial laboratory or by the Contractor subject to acceptance by the project engineer / project inspector. Should the Contractor elect to establish testing facilities, no work requiring testing shall be permitted until the Contractor's facilities have been inspected and accepted by the Contracting Officer or designated representative. All testing shall be performed at no additional cost to the Government.

4.2 Cement: Cement shall be tested as prescribed in the referenced specification under which it is furnished. Cement may be accepted on the basis of mill tests and the manufacturer's certification of compliance with the specification, provided the cement is the product of a mill with a record for the production of high-quality cement for the past three years.

4.3 Aggregate: Aggregate samples for laboratory testing shall be taken in conformance with ASTM D 75 and tested in accordance with ASTM C 136.

4.4 Samples for Mixture Proportioning: Mix design studies and tests shall be made in accordance with ASTM C 78 and C 192, and the test results submitted for approval.

5. SUBMITTALS:

5.1 Concrete Mix Design: The Contractor shall develop and submit, in four copies, a proposed concrete mix design prior to placement. The mix design shall indicate the weight of each ingredient of the mixture. No concrete shall be placed prior to approval of the proposed mix design. No deviation from the approved concrete mix design will be permitted without prior approval from the Contracting Officer.

5.2 Laboratory Test Results: Within 24 hours of physical completion of laboratory testing, three copies of test results shall be submitted for approval.

5.3 Certification: Manufacturer's certifications may be submitted for approval by the Contracting Officer rather than laboratory test results for proposed materials. Certificates should certify compliance with the appropriate specification referenced herein.

6. DELIVERY AND STORAGE OF MATERIALS:

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6.1 Cement: Cement may be furnished in bulk or in suitable bags used for packaging cements and shall be stored in a manner to prevent absorption of moisture.

6.2 Aggregates: Aggregates shall be handled and stored in a manner to avoid breakage, segregation, or contamination by foreign materials.

7. WEATHER LIMITATIONS:

7.1 Concrete shall not be placed when weather conditions detrimentally affect the quality of the finished product. No concrete shall be placed when the air temperature is below 40 degrees F. in the shade. When air temperature is likely to exceed 90 degrees F., the deposited, and the surface of such placed concrete shall be kept damp with a water fog until the approved curing medium is applied.

8. NOT USED

9. NOT USED

10. MATERIALS:

10.1 Coarse Aggregate

10.1.1 Composition: Coarse aggregate shall consist of gravel, crushed gravel, crushed stone, or a combination thereof.

10.1.2 Quality: Aggregate as delivered to the mixers shall consist of clean, hard, unweathered, and uncoated particles. Dust and other coatings shall be removed from the coarse aggregates by adequate washing.

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

10.1.4 Size and Grading: The maximum nominal size of the coarse aggregate shall be 1/2-inch. The coarse aggregate shall be well graded within the limits specified, and when tested in accordance with ASTM C 136, shall conform to the following grading requirements as delivered to the batching hoppers:

COURSE AGGREGATE GRADATIONS

Sieve Size Percent Passing 3/4” 100 1/2” 90-100 3/8” 40-70 #4 0-15 #8 0-5

2575- 4

10.2 Fine Aggregate

10.2.1 Composition: Fine aggregate shall consist of either natural sand, manufactured sand, or a continuation of natural and manufactured sand, and shall be composed of clean, hard, durable particles.

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

10.2.3 Grading: Grading of the fine aggregate as delivered to the mixer shall conform to the following requirements when tested IAW ASTM C 136:

FINE AGGREGATE GRADATIONS

In addition, the fine aggregate, as delivered to the mixer, shall have a fineness modulus of not less than 2.40 nor more than 2.90.

10.3 Air-Entraining Admixtures: Air-entraining admixture shall conform to ASTM C 260.

10.4 Cement: Cement shall be Portland cement conforming to ASTM C 150, Type III

, high strength, high early. At the option of the Contracting Officer or designated representative, Type I cement shall be submitted for approval by the Contracting Officer.

10.5 Curing Materials:

10.5.1 Membrane-forming curing compound shall be a pigmented type conforming to ASTM C 309.

10.6 Water: Water shall be clean, fresh, and free from injurious amounts of oil, acid, salt, alkali, organic matter, or other deleterious substances. Water approved by Public Health authorities for domestic consumption may be accepted for use without being tested. Water that is of questionable quality, in the opinion of the Contracting Officer or designated representative, shall be tested.

11. CONDITIONING OF EXISTING PAVEMENT:

Sieve Size Percent Passing 3/8” 100 #4 95-100 #8 80-90

#16 60-80 #30 30-60 #50 12-30

#100 2-10

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11.1 Preparation of Existing Surfaces: In the area to be patched, the surface of the existing concrete shall be removed to a minimum depth of two inches and to such additional depth where necessary to expose a surface of sound, unweathered concrete that is uncontaminated by oils, greases, or deicing salts or solutions. A vertical saw cut at least two inches deep shall be made a minimum of one inch outside of the area to be repaired. The surface shall be thoroughly cleaned by sweeping and blowing with compressed air. Area showing traces of oils or grease shall be cleaned by sand blasting.

11.2 Preparation of Joints: Joint-sealing and expansion-joint materials shall be removed flush with the prepared surface, and, if on the pavement surface to be patched, shall be removed by sandblasting. The use of solvents will not be permitted. Care shall be used to prevent bonding of the adjacent concrete slabs at the location of the existing joints. Maintenance of these existing joints shall be accomplished by the use of fiberboard or other approved inserts of appropriate dimensions.

11.3 Bonding Course: Prior to placing concrete, the previously prepared surfaces shall be washed with a high pressure water jet followed by an air jet to remove free water. The clean surface shall then be coated with a 1/16-inch thick coating of Portland cement bonding grout. The cement grout shall be placed in one application, just prior to concrete placement, with the use of mechanical combination, mixing and spraying equipment, or shall be applied in two coats with stiff brushes.

The first brush coat shall be scrubbed into the concrete surface, followed by an additional brush coat to obtain the required thickness. When the brush method is used, the initial coat may be allowed to dry; however, the final coat shall be applied just prior to placement of the concrete.

11.3.1 Portland cement grout components shall be mixed in the proportions given here: Mixture shall be one part fine aggregate to one part cement weight, with five gallons of water per 94 lb sack of cement. Fine aggregate shall be graded as shown in paragraph 10.2.3.

12. BATCHING, MIXING AND PROPORTIONING:

12.1 Equipment: The Contractor shall provide adequate facilities for the accurate measurement and control of each of the materials entering the concrete. The Contracting Officer or designated representative shall have free access to the batching and mixing plant at all times. Mixing equipment shall be capable of combining the aggregate, cement, admixture, and water into a uniform mixture and discharging this mixture without segregation.

12.2 Conveying: Concrete shall be conveyed from mixer to repair area as rapidly as practicable by methods that will prevent segregation or loss of ingredients.

12.3 Facilities for Sampling: Suitable facilities shall be provided for readily obtaining representatives samples of aggregate and concrete for uniformity test purposes. Necessary platforms, tools, and equipment for obtaining samples shall be furnished by the Contractor.

12.4 Mix Proportions: The proportions of materials entering into the concrete mixtures shall be in accordance with the approved job-mix formula. The proportions shall be changed whenever necessary to maintain the workability, strength, and standard of quality required, and to meet the varying conditions encountered during the construction. However, no changes will be made without prior acceptance by the Contracting Officer or designated representative.

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12.5 Measurement: Equipment necessary to measure and control the amount of each material in each batch of concrete shall be provided. Bulk cement shall be weighed, but cement in unopened bags as packed by the manufacturer may be used without weighing. If bagged cement is used, batches shall be proportioned so that fractional bags will not be required. One bag of Portland cement will be considered as weighing 94 pounds. Mixing water and air-entraining admixtures may be measured by volume or by weight. One gallon of water will be considered as weighing 8.33 pounds.

12.6 Workability: The slump of the concrete shall be maintained at the lowest practicable value, not exceeding two inches when tested in accordance with ASTM C 143.

13. PLACING:

13.1 Concrete shall be placed within 45 minutes from the time all ingredients are charged into the mixing drum, before the concrete has obtained its initial set, and while the bonding course is still wet. The temperature of the concrete, as deposited in the form, shall be not less than 40 degrees F.

nor more than 90 degrees F. Concrete shall be deposited in such a manner as to require a minimum of re-handling, and the placement shall be in such a manner as to require a minimum of re-handling, and the placement shall be in such a manner so as to least disturb the grout. The placing of concrete shall be rapid and continuous for each area. Workmen shall not walk on the bonding-course surface or in the concrete during placing and finishing operations. The concrete shall be thoroughly consolidated by tamping or by means of suitable vibrating equipment.

14. FIELD TEST SPECIMENS:

14.1 General: Concrete samples shall be furnished by the Contractor, and shall be taken in the field and tested to determine the slump, air content, and compressive strength of the concrete. Test cylinders shall be made for determining conformance with the strength requirements of these specifications and, when required, for determining the time at which pavements may be placed in service. The air content shall be determined in conformance with ASTM C 173. The Contractor shall furnish all materials, labor, and facilities required for molding, curing, and protecting test beams at the site and under the supervision of the project engineer / project inspector. Curing facilities for test cylinders shall include furnishing and operating water tanks equipped with temperature-control devices that will automatically maintain the temperature of the water at 73 degrees F. plus or minus five degrees F. The Contractor shall also furnish and maintain at the site, boxes or other facilities suitable for storing the specimens while in the mold at a temperature of 73 degrees F. plus or minus 10 degrees F. Tests of the fresh concrete and of the hardened concrete cylinders shall be made by and at the expense of the Contractor.

14.2 Specimens for Strength Tests: Compressive test cylinders shall be made each shift that concrete is placed. Each group of test cylinders shall be molded from the same batch of concrete, and shall consist of a sufficient number of specimens to provide two compressive-strength tests at each test age. One group of specimens shall be made during the first half of each shift, and the other during the last portion of the shift. However, at the start of paving operations and each time the aggregate source, aggregate characteristics, or mix design is changed, one additional set of test cylinders shall be made.

15. FINISHING

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15.1 Finishing operations shall be started immediately after placement of the concrete. The finished surfaces of patched areas shall have a surface texture approximating that of the adjacent undisturbed pavements.

16. CURING:

16.1 General: Concrete shall be cured by protection against loss of moisture and rapid temperature changes for a period of not less than 7 days from the beginning of the curing operation.

Unhardened concrete shall be protected from rain and flowing water. The Contractor shall have all equipment needed for adequate curing and protection of the concrete on hand and ready to install before actual concrete placement begins. Failure to comply with curing requirements shall be cause for immediate suspension of concreting operations.

16.2 Membrane-forming curing compound shall be applied immediately to exposed concrete surfaces after finishing. The curing compound shall be applied with an overlapping coverage that will give a two-coat application at a coverage of not more than 200 square feet per gallon for both coats.

16.3 When application is made by hand-operated sprayers, the second coat shall be applied in a direction approximately at right angles to the first coat.

16.4 Concrete shall be properly cured at joints, but no curing compound shall enter joints that are to be sealed with joint-sealing compounds. The compound shall form a uniform, continuous, cohesive film that will not check, crack, or peel, and that will be free from pinholes and other imperfections.

16.5 Concrete surfaces that are subjected to heavy rainfall within three hours after the curing compound has been applied shall be re-sprayed at the coverage specified above and at no additional cost to the Government.

16.6 Areas covered with curing compound that are damaged by pedestrian and vehicular traffic or by subsequent construction operations within the specified curing period shall be re-sprayed at no additional cost to the Government.

17. FINISH TOLERANCE:

17.1 The finished surfaces of patched areas shall meet the grade of the adjoining pavements and shall not deviate more than 1/8-inch from a true plan surface within the patched area.

18. PAVEMENT PROTECTION:

18.1 The Contractor shall protect the patched areas against damage prior to final acceptance of the work by the Government. Traffic shall be excluded from the patched areas by erecting and maintaining barricades and signs until the completion of the curing period of the concrete.

19. JOINTS

19.1 Joint shall conform in detail and be in alignment with the existing joints. Joints shall be sealed as specified in SECTION: RESEALING RIGID PAVEMENT JOINTS AND CRACKS. Joint

2575- 8 resealing is paid as a separate payment item under: CONCRETE JOINT SEALING.

20. CONTRACTOR’S QUALITY CONTROL (CQC):

20.1 The Contractor’s quality controller shall establish and maintain quality control of the work covered under this project and each delivery order to ensure compliance with the contract requirements, including but not limited to the items listed below:

20.1.1 The CQC shall ensure that the spall repairs occur on sound concrete.

20.1.2 The CQC shall ensure that the concrete is properly mixed and cured.

20.1.3 The CQC shall mark out the spalled areas that require repair in the designated work areas and then shall measure actual quantities of spall repairs performed by the contractor.

21. UNIT OF MEASUREMENT AND PAYMENT: Per the Bid Schedule and Section 1020.

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