02520.doc

SECTION 02520

REPAIR OF AIRFIELD PAVEMENT SURFACES

RIGID PAVEMENT SYSTEMS

PART 1 -

GENERAL

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.

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

CRD-C 55-92

Test Method for Within-Batch

Uniformity of Freshly Mixed

Concrete(used for determination of the minimum time of mixing)

CRD-C 100-75

Method of Sampling Concrete Aggregate and Aggregate Sources, and Selection of Material for Testing

CRD-C 104-80

Method of Calculation of the Fineness

Modulas of Aggregate

CRD-C 112-69

Method of Test for Surface Moisture in Aggregate by Water Displacement

CRD-C 119-91

Standard Method of Test for Flat and Elongated Particles in Coarse

Aggregate (ASTM D 4791-89)

CRD-C 300-90

Corps of Engineers Specifications for

Membrane-Forming Compounds for Curing

Concrete

CRD-C 400-63

Requirements for Water for Use in Mixing or Curing Concrete

1.2 American Society for Testing and Materials (ASTM) Publications:

A 184M-90

Specification for Fabricated

Deformed Steel Bar Mats for

Concrete Reinforcement

A 497-4a

Specification for Steel Welded

Wire Fabric, Deformed, for

A 615M-94

Specification for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement

A 616M-93

Specification for Rail-Steel

Deformed and Plain Bars for

A 617M-90

Specification for Axle Steel

Deformed and Plain Bars for

C 29/29M-91

Test Method for Unit Weight and Voids in Aggregate

C 31-91

Practice for Making and Curing

Concrete Test Specimens in the Field

C 33-94

Concrete Aggregates

C 70-94

Test Method for Surface Moisture in Fine Aggregate

C 78-94

Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)

C 94-94

Specification for Ready Mixed Concrete

C 117-95

Test Method for Material Finer Than

75-µm (No. 200) Sieve in Mineral

Aggregates by Washing

C 123-94

Test Method for Lightweight Pieces in Aggregate

C 136-5a2

Test Method for Sieve Analysis of Fine and Coarse Aggregates

C 142-78 (1990)

Test Method for Clay Lumps and

Friable Particles in Aggregates

C 143-90a

Test Method for Slump of Hydraulic

Cement Concrete

C 150-95

Specification for Portland Cement

C 172-90

Practice for Sampling Freshly Mixed

Concrete

C 173-94a

Test Method for Air Content of

Freshly Mixed Concrete by the

Volumetric Method

C 174-87(1991)

Test Method for Measuring Length of Drilled Concrete Cores

C 192-90a

Concrete Test Specimens in the Laboratory

C 231-91b

Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method

C 260-94

Specification for Air Entraining

Admixtures for Concrete

C 494-90

Specification for Chemical Admixtures for Concrete

C 618-94a

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

Portland Cement Concrete

C 881-90

Specification for Epoxy-Resin Base

Bonding Systems for Concrete

D 422-63(1990)(1

Test Method for Particle Size

Analysis of Soils

D 558-82(1990)

Test Method for Moisture-Density

Relations of Soil Cement Mixtures

D 559-89

Test Method for Wetting and Drying Tests of Compacted Soil-Cement Mixtures

D 1241-68(1994)

Specification for Materials for

Soil-Aggregate Subbase, Base, and

Surface Courses

D 1556-90

Test Method for Density of Soil in Place by the Sand Cone Method

D 1557-91

Test Method for Laboratory

Compaction Characteristics of

Soil Using Modified Effort

(56,000 ft-lbf/ft3 (2,700 kN-m/m3))

D 1632-87

Soil Cement Compression and Flexure

Test Specimens in the Laboratory

D 1633-84(1990)

Test Method for Compressive Strength of Molded Soil-Cement Cylinders

D 1751-83(1991)

Specification for Preformed Expansion

Joint Filler for Concrete Paving and Structural Construction

(Nonextruding and Resilient

Bituminous types)

D 1752-84(1992)

Specification for Preformed Sponge

Rubber and Cork Expansion Joint

Fillers for Concrete Paving and

Structural Construction

D 2167-94

Test Method for Density and Unit

Weight of Soil In Place by the

Rubber Balloon Method

D 2487-93

Classification of Soils for

Engineering Purposes (Unified

Soil Classification System)

D 2922-91

Test Method for Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth)

D 2937-94

Test Method for Density of Soil in

Place by the Drive-Cylinder Method

D 3017-88(1993)

Test Method for Water Content of Soil and Rock in Place by

Nuclear Methods (Shallow Depth)

D 4318-93

Test Method for Liquid Limit, Plastic Limit, and Plasticity

Index of Soils

E 548-94

Guide for General Criteria Used for

Evaluating Laboratory Competence

2.

Quality Assurance/Quality Control (QA/QC) Procedures:

2.1 CONSTRUCTION MATERIAL TESTING (QA) BY GOVERNMENT: The Government will use the results of material testing accomplished by the Contractor to evaluate the construction for acceptance. The Contractor shall provide copies of all quality control testing results and product certifications to the Contracting Officer Representative. All test results will be reported the Contracting Officer within 24 hours of the completion of the respective tests.

2.2 Construction Material Testing (QC) by Contractor: The Contractor shall retain the services of an independent commercial testing laboratory, herein after referred to as the QC LAB. The QC LAB shall perform those quality control (QC) functions which are necessary to monitor the work. The QC LAB shall do concrete mix designs, soils analysis for compaction control, and supporting construction process monitoring. The minimum daily monitoring requirements are described in paragraph Contractor Quality Control. Within 15 days of the Notice to Proceed date, the Contractor shall submit the qualifications statement of the QC LAB. The Government will review the qualifications of the laboratory and, if necessary, visit the QC LAB. The Contracting Officer will, within 7 working days from the date that all qualifications data is received, either approve or reject the proposed laboratory. Evaluation criteria which will be used to determine the suitability of the QC LAB shall include, as minimum, local area industry standards, ASTM E 548, and respective State Highway Department certifications when applicable.

2.3 Mixture Proportioning Studies: After an aggregate source is approved, described in paragraph Material Acceptance Testing, but at least 30 days before materials are placed at the work, the QC LAB shall do mixture proportioning studies. Proportioning studies shall be accomplished for the Portland Cement concrete mixtures. The results of the proportioning studies and the recommended mix designs shall be submitted to the Contracting Officer. The Contracting Officer will issue written notice that the mix designs are appropriate before the Contractor places materials on the work.

2.4 Construction Test Section: Before proceeding with the work the Contractor shall demonstrate that he can perform to the intent of this specification. The Contractor shall place a test section in Branch A05C, in an area designated by the Contracting Officer. The Contractor shall demonstrate the ability to do pavement removal, subgrade preparation, base placement, and concrete mixing, placing and finishing. The Contractor shall demonstrate work for both partial and full depth concrete repairs. The construction of joints, protection of the work, and quality control procedures will be incorporated into the test section. A test section which does not meet the performance requirements of these specifications will be removed from the work at the expense of the Contractor. All procedures and materials used by the Contractor to construct an acceptable test section shall be the standard of evaluation for performance of the work. The Contractor shall receive written approval of the test section from the Contracting Officer before proceeding with the work. The Government will expect to see equipment, materials, and procedures used for the approved test section incorporated into the work.

3.

MATERIAL ACCEPTANCE AND TESTING:

3.1 Pre-construction Sampling and Testing:

3.1.1 Aggregates for Concrete Mixtures: Aggregates shall be produced from sources of the Contractors choosing. The aggregates will be tested to determine specific gravity, absorption, Los Angeles Abrasion, sulfate soundness, freeze and thaw durability, alkali or carbonate reaction, and organic impurities. A petrographic analysis will be performed unless there is a record of proven performance of at least 5 years for the aggregate source.

3.1.2 Sampling and Testing: The Contractor shall accomplish aggregate sampling and testing of the aggregates for quality determination. The Contracting Officer Representative will observe the aggregate sampling. Split samples will be provided to the Government. All quality testing results will be provided to the Contracting Officer at least 10 days before the start of the mix proportion study. The Contracting Officer representative will either approve or reject the aggregate source within 7 days from the date all qualifying information is received.

3.1.3. Cement: Cement to be used in the work shall be from a producer which has industry recognition as a manufacturer. The Contractor shall submit, not later than 15 days after the Notice to Proceed date, data which identifies the brand of the cement to be used and the engineering characteristics of the proposed cement. The Contracting Officer representative shall either accept or reject the source of the cement within 7 days from the submittal of all qualifying information.

3.1.4. Admixtures: The Contractor may use admixtures. The selection of the admixtures is the option of the Contractor. Within 15 days after the Notice to Proceed date the Contractor shall provide a list of those admixtures proposed for use in the material mixtures. The Contractor assumes all responsibility for the use of admixtures.

3.1.4.1. Pozzolan: The Contractor shall identify the source and the engineering characteristics of the pozzolan proposed for use in the concrete or soil cement mixture. All mix proportion studies will be accomplished with the pozzolan included.

3.1.4.2. Manufactured Admixtures: The Contractor shall submit a manufacturer statement for each admixture proposed for use. The statement shall describe the characteristics of the admixtures, the expected performance of the mixes with the admixture, and specific statements about the compatibility of the admixtures with the proposed aggregates, cement, and other admixtures when multiple products are proposed. All mix proportion studies will be accomplished with the admixtures included in the trial mixes.

3.1.5. Curing Compound: At least 30 days before the material is used on the work, the Contractor shall submit a statement of the manufacturer that warrants that the material conforms to the intent and the technical requirements of these specifications. A sample of the material proposed for use on the work will be provided to the Government.

3.1.6. Epoxy-resin Material: At least 30 days before the material is used on the work, the Contractor shall submit a statement of the manufacturer that warrants that the material conforms to the intent and the technical requirements of these specifications. When epoxy resin arrives at the job site, a sample of the material proposed for use on the work will be provided to the Government.

4.

CONSTRUCTION TOLERANCES AND ACCEPTANCE CRITERIA:

4.1 Construction Tolerances: Variation in the thickness of the concrete surface caused by grade irregularity in the subgrade or the base thickness will not be permitted. Surface smoothness criteria will be applied for both full depth and partial depth repairs. Density criteria will apply to the subgrade and the base course when doing full depth repairs.

4.1.1 Subgrade and Base Course Smoothness: When full depth repairs are made for a full slab, a partial slab, or multiple slabs of adjacency the subgrade and the base finished elevation surfaces will be checked for smoothness using a rigid straight edge of suitable length. The finished surfaces will not vary more than 13 millimeters (1/2-inch) when checked with the straightedge.

4.1.2. Subgrade and Base Course Compaction: The density of the placed or stabilized materials will be determined by testing. A minimum of three density tests will be accomplished within each area of full depth repair. The placed materials will be evaluated for consistency. Areas of the repair which vary by more than three percentage points (3%) of optimum within an area will be cause for mitigation. Mitigation will be accomplished using the procedures described in paragraph Deficiencies and Corrections.

4.1.3. Surface Smoothness: The finished surfaces of rigid pavements shall be within the tolerances specified in TABLE II when using a 3.6-meter- (12-foot-) long rigid straight edge. The procedure for the determination of smoothness is described in paragraph Surface Smoothness Determination.

TABLE II

SURFACE SMOOTHNESS CRITERIA

AIRFIELD PAVEMENTS

Pavement Category

Direction of Testing Tolerance

Runways and Taxiways Longitudinal

3 MM (1/8”)

Transverse

6 MM (1/4”)

Aprons and Hardstands

5 MM (3/16”)

5 MM (3/16”)

Other Paved Areas

4.1.4. Thickness: Deficiencies in the thickness of placed materials, either base course or surface course, will be mitigated using the procedures in paragraph Deficiencies and Corrections. Permissible deviations in thickness will be up to 13 millimeters (1/2-inch).

4.2.

Finished Surfaces Evaluation Techniques: The finished surface of the concrete, and the subgrade and cement stabilized base for full depth repairs, will be evaluated for surface smoothness and thickness. Subgrade and base course, soil materials, will be evaluated for density.

4.2.1. Equipment: The Contractor shall furnish and maintain at the job site a rigid straightedge which is to be used to check the surface smoothness of constructed surfaces. The straightedge used to check the smoothness of concrete surfaces will be 3.6 meters (12 feet) in length. The straightedge should be of I-beam or channel construction of a light-weight material; e.g., aluminum.

4.2.2. Surface Smoothness Determinations: When the surface of the subgrade, base course, or concrete, respectively as applicable, has been finished it will be checked for smoothness. Surface smoothness determinations will be witnessed by the Government. The straight edge will be placed on the surface and moved about to reveal surface irregularities. For checking concrete surfaces at the joint with other surfaces, the straightedge shall be held in contact with the surface and advanced along a straight line across the jointed surface. When a high area is found the height will be determined by placing the middle of the straight edge at the high area and measuring the distance between the pavement and the straightedge with one end of the straightedge grounded. One half the measurement will be the height of the high area.

4.2.3. Thickness Determinations: The placed thickness of the pavement, or base thickness for full depth repairs, shall be determined by the Government. The method of thickness determination will be by measurement from the surface to the subgrade and from the surface to the top of the base course.

4.2.4. Concrete Quality Determination: Concrete samples will be taken by the Contractor to determine the slump, air content, and strength of the concrete. The tests are a part of the Contractor quality control program. Concrete samples will be taken a minimum of two times on random selected batches for each day of concrete placement or for each 200 cubic yards of concrete placed, whichever is least.

4.2.4.1. Slump Test: Slump will be maintained within 25 millimeters (1 inch) of the design slump.

4.2.4.2. Air Content: Air content shall be maintained within one-and-one-half percent (1.5%) of the design mix. Air content shall be 6 percent.

4.2.4.3. Strength Tests: One set of test beams shall be made for testing at the ages of 7 days and 28 days.

4.3.

Surface Deficiencies and Corrections:

4.3.1. High Areas: High areas of concrete surfaces shall be reduced either by rubbing the freshly finished concrete with carborundum brick or by grinding of the hardened concrete. Grinding will not be done until the concrete is at least 36 hours old. High areas in subgrade or base course shall be trimmed and the area scarified and compacted.

4.3.2. Thickness Deficiency: When the measurements of the base course or the concrete surface are deficient by more than 13 millimeters (1/2-inch) the deficient layer will be removed and corrections accomplished.

4.3.3. Density Deficiency: When the subgrade or the base course is determined to be less than the required compaction, the effected layer shall be removed, the lower lift will be re-compacted, and the defective lift will be replaced and compacted.

4.3.4. Concrete Quality Deficiency:

4.3.4.1. Slump and Air Content: When two consecutive tests or more than twenty percent (20%) of the individual tests (one test in the last five) are outside the tolerance concrete placing on the work will cease. The mixture proportions shall be evaluated and the cause of non-compliance determined. The mixture proportions shall be changed if necessary.

4.3.4.2 Strength Deficiency: When the average of any five consecutive 7-day strengths; or, when one (1) of the last five consecutive tests of the same age group are less than the design mix minimum, the concrete placement on the work will cease. The cause of the low strength will be determined before proceeding with concrete placement on the work. When necessary the mixture proportions will be changed. Concrete which will not meet the 28-day strength requirement shall be removed and replaced by the Contractor without cost to the Government.

5.

ACCEPTANCE OF CONSTRUCTION PROCEDURES:

5.1 Plant and Equipment: The Contracting Officer representative will have access to the mixing plant, aggregate and soil storage area, and equipment during the progress of the work. Equipment determined to be detrimental to the progress of the work will be taken out of service and shall be replaced by the Contractor.

5.2.

Construction Methods: The Contracting Officer representative will review and either approve or reject special construction methods.

5.2.1. Cold Weather Requirements: The Contractor shall prepare a cold weather concreting plan. The plan shall describe the materials and procedures to be used by the Contractor when protection is required. The Contractor shall describe in the plan the prevailing weather conditions which would require use of the cold weather provisions.

5.2.2. Hot Weather Conditions: The Contractor shall prepare a hot weather concreting plan. The plan shall describe the materials and procedures to be used by the Contractor when protection is required. The Contractor shall describe in the plan the prevailing weather conditions which would require use of the hot weather provisions.

5.2.3.

Demolition: The Contractor shall prepare and submit for approval or rejection a demolition plan. The plan shall describe the methods to be used for removal of existing pavements and the protection of pavement designated to remain. Debris from the demolition will be removed from the job site daily. Dust and fugitive debris shall be controlled at all times. Debris from the demolition shall be controlled so that it does not become a nuisance in areas outside of the immediate area of construction.

5.2.3.1. Environmental Protection: Demolition work will be performed to comply with environmental controls, policies and directives.

5.2.3.2. Burning and Explosives: Burning and the use of explosives will not be permitted.

5.3.

Pavement Construction Test Section:

5.3.1. Construction Methods: The Contractor shall place a pavement replacement and/or repair test section at a location on the work which will be designated by the Contracting Officer. When a satisfactory test section is constructed the section will become a portion of the project work. A minimum of one full depth repair and one partial depth repair will be included in the test section. The Contractor shall include the quality control procedures into the test section.

5.3.2. Test Section Acceptance: The Contracting Officer and his representative will observe the test section work being performed. If the section is rejected, the reasons shall be specifically documented. The Contractor shall remove and replace test sections which are not accepted by the Government. The test sections will be repeated until the Contractor successfully demonstrates an acceptable construction procedure.

6.

MEASUREMENTS: SEE SECTION 01025

PART 2 - PRODUCTS

8.

MATERIALS:

8.1.

Cement: Cement may be furnished in bulk or packages. When cement is furnished in packages, batch proportions shall be adjusted to require complete packages. Portland Cement shall conform to ASTM C 150, Type I.

8.2.

Admixtures: The Contractor shall have the option to use admixtures. When admixtures will be used they will be included in the proportions for concrete mix design and trial batches.

8.2.1. Pozzolan: Pozzolan, when used as a mineral admixture, shall conform to ASTM C 618, Class F or C. When fly ash is used there will be a minimum of 5-1/2 bags of Portland Cement (approximately 234 kilograms [517 pounds]) per 0.76 cubic meters (1 cubic yard) of concrete mix yield. The fly ash shall be considered cementitious material and the weight of fly ash added to the weight of portland cement will be the "total cementitious material." The total amount of fly ash used shall not be less than 15 percent nor more than 25 percent by weight of the total cementitious material in the concrete mix.

8.2.2. Air-Entraining Admixtures: The air entraining admixture shall conform to ASTM C 260.

8.2.3. Accelerator: Calcium chloride shall not be used.

8.2.4. Retarder: A retarding admixture shall meet the requirements of ASTM C 494, Type B or D. The six month and the one year compressive strength tests are waived.

8.2.5. Water-Reducer: A water-reducing admixture shall meet the requirements of ASTM C 494, Type A. The six month and the one year compressive strength tests are waived.

8.3.

Curing Materials: Curing compounds shall be white pigmented membrane-forming conforming to CRD-C 300.

8.4.

Dowels: Dowels shall be cut to length before delivery to the site. They shall be clean, straight, and free of loose flaky rust and scale. Dowels shall be plain steel bar conforming to ASTM A 615, Grade 40 or 60; ASTM A 616, Grade 50 or 60; or ASTM A 617, Grade 40 or 60.

8.5.

Tie Bars: Tie bars shall be deformed steel bars conforming to ASTM A 615, A 616, or A 617.

8.6.

Reinforcement: All reinforcement shall be clean and free of loose flaky rust or scale, free of oil or grease, or free of coatings that might reduce the bond between the steel and the concrete.

8.6.1. Bar Mats: Bar mats shall conform to ASTM A 497.

8.6.2. Wire Fabric: Welded steel wire fabric shall conform to ASTM A 497.

8.6.3. Deformed Wire Fabric: Welded deformed steel wire fabric shall conform to ASTM A 615, A 616, or A 617.

8.7.

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

8.8.

Epoxy-Resin: Epoxy resin materials shall be two component materials conforming to the requirements of ASTM C 881. The materials shall be Type II. Epoxy resin used for anchoring dowel bars shall be Type III.

8.9.

Water: Water shall be free from deleterious substances and shall comply with CRD-C 400.

8.10.

Coarse Aggregate for Concrete Mixes: Coarse aggregate shall be crushed gravel, crushed stone, or a combination thereof. Aggregates shall be clean, hard, uncoated particles which meet the requirements specified in ASTM C 33. Particles shall be generally cubical in shape. The quantity of flat or elongated pieces in any size group shall not exceed 20 percent by weight when determined by procedures of CRD-C 119. A flat particle is defined as one having a ratio of width to thickness greater than 3; an elongated particle is one having a ratio of length to width greater than 3.

8.10.1. Aggregate Size and Grading: The nominal maximum size of the coarse aggregate shall be 19 millimeters (3/4 inches).

8.10.2. Deleterious Substances: The amount of deleterious substances in each size group of coarse aggregate shall not exceed the limits given in Table 3, ASTM C 33, except that clay and friable particles shall not exceed 1.5 percent.

8.11.

Fine Aggregate: Fine aggregate shall be natural sand, manufactured sand, or a combination of the two.

8.11.1. Grading: Grading of the fine aggregate shall conform to the requirements of ASTM C 33. The fine aggregate shall have a fineness modulus of not less than 2.30 nor more than 3.10. The grading of the fine aggregate shall be consistent such that the fineness moduli will not vary more than 0.20 from the average moduli of the sand used for the mix design. Fineness modulus shall be determined by CRD-C 104. When pozzolans are used as an admixture, the material passing the No. 50 and No. 100 sieve sizes shall be reduced as allowed in ASTM C 33.

8.11.2. Deleterious Substances: The amount of deleterious substances shall not exceed the limits given in Table 1, ASTM C 33.

9.

CONCRETE MIXTURE PROPORTIONING: Concrete shall be a mixture of cement, water, fine and coarse aggregates, and admixtures. Admixtures are the option of the Contractor. The Contractor shall be responsible for determining the proportions of the concrete materials.

9.1.

Flexural Strength: Proportioning of the concrete materials shall be such that a flexural strength of 4482 kPa (650 psi) is attained at 28 days when tested using the procedures of ASTM C 78. The Contractor shall do the mix design studies. Curves will be developed for the selected mix at three water cement ratios using strength of specimens at 7 days age, 14 days age, and 28 days age. The water cement ratios used for the strength gain curves shall be in (0.03 increments above the design mix. The slumps of the respective mixes will be reported. The strength gain curves will be used by the Government for acceptance of placed concrete using the procedures described in paragraph SURFACE EVALUATION AND ACCEPTANCE: Concrete Quality Determination.

9.2.

Air Content: The air content by volume based upon measurements made immediately after discharge from the mixer shall be 6.0 percent plus 2.0 or minus 1.5 percent when determined using ASTM C 231.

9.3.

Slump: The concrete slump shall be determined in accordance with ASTM C 143.

10.0 Not Used

END PART 2 - PRODUCTS

PART 3 - EXECUTION

11.

DEMOLITION: Before beginning any demolition work, the Contractor shall survey the site. Work shall not begin until the Contractor can provide assurance that the work can be executed the way the drawings and specifications have established the intent.

11.1.

Protection of Existing Pavement: The Contractor shall take all necessary precaution to avoid damaging pavements designated to remain. Any damage to existing pavement will be repaired by the Contractor without cost to the Government.

11.2.

Disposition of Material: All materials removed by the Contractor become the property of the Contractor and shall be disposed of off base. Existing ground rods or aircraft tiedowns will be salvaged and re-installed by the Contractor. At full depth repair areas, existing base course materials, or other materials below the existing concrete, will be excavated to a depth which will allow installation of the replacement pavement section.

11.3.

Unsatisfactory Materials: Unsatisfactory materials shall be any material classified using ASTM D 2487 as Pt, OH, OL or any soil comprised of vegetative matter, sod, mulch, or rubbish. Unsuitable materials shall be those which classify as MH or CH. Unsatisfactory or unsuitable materials shall be removed and replaced with select backfill.

11.4.

Backfill: Backfill material shall be placed in maximum 101-millimeter (4-inch) loose layers and compacted to the grade and cross-section.

12.

PARTIAL DEPTH REPAIR OF PAVEMENTS: The Contractor shall reference Engineers drawings for partial depth spall repairs. The intent of the partial depth repair is to restore the slab edges for effective joint sealing and to deter further deterioration.

12.1.

Establishing Repair Boundaries: The limits of the unsound concrete shall be determined by sounding with a steel rod. The rod shall be dropped from a height of 100 to 150 millimeters (4 to 6 inches). The sounding will produce a dull sound in areas of delaminated concrete. A sharp ringing sound will be heard when there is sound concrete.

12.1.2. Sawcutting: A diamond blade sawcut shall be made at the limits of the repair boundary which shall be a minimum of three inches into sound concrete and outside the unsound concrete. The boundaries shall be sawcut in a rectangular pattern square to the slab edges. Sawcuts at right angles, including existing joints, shall be overlapped by at least 25 millimeters (1 inch). The depth of sawcut shall be 51 millimeters (2 inches), minimum. When the boundaries of multiple partial depth repairs areas are closer than 609 millimeters (24 inches), the repair areas shall be combined as one repair. A sawcut of minimum depth shall be made along the joint face to remove old joint sealant and to make a clean vertical face at the joint.

12.1.3. Removal of Existing Concrete: Existing concrete within the boundaries of the repair shall be removed by chipping with pneumatic tools. Pavement breakers or hydraulic rams shall not be used. Concrete will be removed to the depth of the sawcut or to sound concrete, whichever is deeper. After all concrete has been removed the faces will be cleaned and sounded. Sounding within the limits of the repair will ensure that all damaged and unsound concrete has been removed. When the depth of the unsound concrete exceeds one-half of the slab depth, the work will stop. The Government will inspect the area and either allow patching or direct the Contractor to proceed with a full depth repair. Under no circumstances will a partial depth repair be allowed to rest on a dowel bar.

12.2.

Patching and Finishing:

12.2.1. Cleaning: The exposed faces of the patch area shall be washed with high pressure water and air-blown dry. There shall be no residual material left on the exposed concrete face.

12.2.2. Joint Preparation: The potential for bond between the partial depth patch and the facing joint shall be eliminated by placing a compressible insert along the joint prior to patching. The joint formed between the partial depth patch and the facing joint shall have a width less than or equal to the existing joint width.

12.2.3. Concrete Surfaces Preparation: The exposed areas of the patching area will be coated with an epoxy resin bonding agent. The agent shall be applied by the instructions of the manufacturer. Application shall be by stiff bristle brush to assure that a thin coat is applied to all exposed patch areas. The bonding agent shall not be allowed to puddle. Concrete patching material shall not be placed until the bonding agent is tacky.

12.2.4. Patching Materials Placement and Finishing: Fresh concrete shall be placed into the patch area and consolidated with hand tools or a small vibrator up to 25 millimeters (1 inch) in diameter. When a vibrator is used, the probe will be extracted at the first sign of water forming around the probe. The surface shall be finished to the cross-section of the existing pavement. A screed shall be used to move surface material from the center of the patch areas to the outsides. The edges which meet with sawcuts shall not be edged. The finish surface shall be given a burlap drag or broom finish. A curing compound shall be applied and the area protected from damage. A joint seal will be applied when the patch is cured.

13.

FULL DEPTH REPAIR OF PAVEMENTS: The Contractor shall reference Engineers drawings for full depth concrete repairs. The intent of the full depth repair is to restore the damaged areas to the original condition and make the repair a part of the existing slab. The repair is to be tied to the parent slab.

13.1.

Establishing Repair Boundaries: Full depth slab repair is required where there is a corner break, patch deterioration (or where a patch depth exceeds one-half the slab depth), shattered slabs, or full depth longitudinal or transverse cracks which have opened and are spalling. Full slab replacement is required when the repair to a distress area will exceed one-half the slab width. A minimum repair width of 1.8 meters (6 feet) is required for full depth repair, unless utility patches are being replaced.

13.1.1. Sawcutting: The repair boundaries shall be diamond blade sawcut. Full depth sawcuts shall be made at existing joint faces. A sawcut of a minimum depth of 51 millimeters (2 inches) shall be made at the boundaries of the repair which are not at a joint. All sawcuts shall be square to the existing joints forming a rectangular pattern around the area of the full depth repair. All partial depth sawcuts shall be a minimum of two feet from an existing joint or crack. All sawcuts shall overlap at sawcut intersections.

13.1.2. Removal of Existing Concrete: There are two methods for concrete removal. The removal shall not result in the spalling or the cracking of concrete pavement designated to remain.

13.1.2.1. The break-up and clean out method is accomplished using pneumatic tools and/or a pavement breaker with removal by backhoe. When this method results in spalling of the slab face designated to remain, the size of the break-out equipment will be reduced or the sawcut shall be made to full depth of the slab. The pavement breaker shall not strike closer than 460 millimeters (18 inches) to the perimeter saw cuts or existing joints. Break-out shall proceed from the center of the repair area to the perimeter saw-cuts.

13.1.2.2. The lift-out method is accomplished using a crane or front end loader to lift the deteriorated concrete out of the repair area. The repair area shall have double full-depth perimeter saw-cuts.

13.2.

Earthwork for Full Depth Repairs: The Contractor shall perform excavation of the materials below the existing concrete to the depth and grade necessary to install the new pavement section. The work generally includes excavation, dressing to grade, shaping, scarifying, and compacting.

13.2.1. Subgrade Compaction Requirements: The in situ material shall be compacted to 90 percent of maximum laboratory value. Testing shall be accomplished using the procedures described in paragraph Contractor Quality Control. Compaction shall be accomplished using equipment which can be operated in the excavation without damage to the prepared surface. Hand operated vibratory compactors shall be used adjacent to exiting pavement designated to remain.

13.3.

Dowel Bar and Tie Bar Placement: Holes for either smooth steel dowel bars or deformed steel tie bars shall be drilled in the appropriate locations of the exposed concrete faces. The holes shall be drilled by a drill mounted in a rigid frame that will prevent drill wandering and will hold the drill horizontal to the pavement surface. The holes shall be drilled 3.0 millimeters (1/8-inch) larger than the bar diameter at one-half the slab thickness at the designated spacing. The holes shall be injected full with epoxy-resin and the bar placed into the pre-drilled holes. The bar shall be turned one revolution and forced to seat. The excess epoxy squeezed from the hole shall be removed from the concrete with a straight edge and the area brushed with a stiff bristle brush. The bar ends coated with epoxy-resin shall be clean and free of all dirt, oil, and other coatings.

13.3.1. Dowel Bar Preparation: Dowels are intended to accommodate the movement of adjoining slabs. The end that extends into the repair area shall be painted and oiled to prevent any bonding with the patch material. Dowels shall not be used at expansion joints.

13.3.2. Tie Bar Preparation: Tie bars are deformed steel which are intended to lock and anchor surrounding concrete. Tie bars are placed at patch interfaces with existing concrete and are not intended to allow movement. Tie bars will be clean and free of any rust, flaking metal, oil, or other coatings.

13.4.

Patching and Finishing:

13.4.1. Cleaning: The exposed faces of the patch area shall be air blown to clean and remove loose debris on the exposed concrete faces. Residual material shall not be left on the concrete faces.

13.4.2. Concrete Surfaces Preparation: The exposed areas of the patching area will be coated with an epoxy resin bonding agent. A bonding agent shall not be applied to the faces of existing joints. Existing joint faces shall be cleaned by air pressure and brushing. The agent shall be applied by the instructions of the manufacturer. Application shall be by stiff bristle brush to assure that a thin coat is applied to all exposed patch areas. The bonding agent shall not be allowed to puddle. Concrete patching material shall not be placed until the bonding agent is tacky.

13.4.3. Patching Materials Placement and Finishing: Fresh concrete shall be placed into the patch area and consolidated using portable spud vibrators. The surface shall be finished to the cross-section of the existing pavement. For repair areas less than 3.6 meters (12 feet) in length, the concrete is to be struck off with a screed operated parallel to the centerline of the pavement. The edges which meet with sawcuts shall not be edged. The surface shall not be over-finished. The finish surface shall be given a burlap drag or broom finish. A curing compound shall be applied and the area protected from damage. The joint seal reservoir of existing joints adjacent to patching shall be sawcut when the concrete has cured. A joint seal will be applied after the patch is cured.

14.

PRODUCTION OF CONCRETE: The batching plant or the truck mixer shall produce a mixture which when tested will conform to the requirements of CRD-C 55. The mixing time for each batch will be determined by using the procedures of CRD-C 55. Each batch product delivered to the work for placement will be consistent as measured by the uniformity tolerances of TABLE III. The uniformity tolerances apply only to the individual within batch characteristics.

TABLE III

UNIFORMITY TOLERANCES IN

CONCRETE MIXERS

Permissible Range in Results

From Three Locations in the

Parameters

Concrete Batch

Weight per cubic foot calculated

0.45 kg (1.0 lb) to an air free basis

Air content, volume percent

1.0

Slump

25 mm (1.0 inch)

Coarse aggregate portion, percent

6.0

Average compressive strength at

10.0

7 days based upon the average of all samples, percent

Water content portion, percent

1.0

15.

CONCRETE CURING AND PROTECTION:

15.1. Curing of Concrete: Concrete shall be protected from loss of moisture for at least seven (7) days. Fresh concrete shall be protected from rain and free water. A uniform coating of a white pigmented membrane-forming curing compound shall be applied to the surface of the fresh concrete as soon as the free water disappears. The compound shall be hand applied at a rate of about 18.6 square meters per 3.8 liters (200 square feet per gallon) from a spray applicator. The compound shall be applied in two coats, the second coat being applied in a direction which is perpendicular to the first coat. Curing compound shall be re-applied to surfaces which have been subject to heavy rainfall within three hours of the initial application of compound.

15.2. Pavement Protection: The Contractor shall protect the pavement from damage prior to acceptance of the work by the Government. Traffic shall be excluded from the repair areas for a minimum of 14 days. Barricades and signs shall be used by the Contractor to protect the work.

16. CONTRACTOR QUALITY CONTROL (QC): The Contractor shall perform the minimum inspection and tests described herein as the quality control program. The results of the inspections and tests requires the Contractor to take an action. The actions, testing and reporting described below are the responsibility of the Contractor. Testing shall be accomplished by an independent testing laboratory which is employed by the Contractor.

16.1.

Inspection Details and Frequency of Inspection: The following are the minimum number of tests or inspections which are to be done by the Contractor.

16.1.1. Concrete Production:

16.1.1.1. Mixer Performance: Before the start of concrete production for placement on the work the uniformity of the mixed concrete shall be determined. Adjustments in the mix or the mixing time shall be made until the results of testing using CRD-C 55 are satisfactory.

16.1.1.2. Fine Aggregate: Once during each 8-hour shift of concrete production, or portion thereof, there shall be one sieve analysis and one determination of fineness modulus. Testing shall be done in accordance with the procedures in ASTM C 136 and CRD-C 104. The fine aggregate shall be sampled at the bin feed. The Contractor shall maintain a fineness modulus control chart with the limits drawn 0.20 units above and below the mix design determination. Moisture contents of the fine aggregate shall be accomplished when the slump of the mixed concrete is out of the specified limits.

16.1.1.3. Coarse Aggregate: Once during each 8-hour shift of concrete production or portion thereof, there shall be a sieve analysis of the coarse aggregate. Samples shall be taken at the bin feed. Moisture contents of the coarse aggregate shall be accomplished when the slump of the mixed concrete is out of the specified limits.

16.1.1.4. Batch Control: A daily record shall be kept of all constituent materials and the portions of each batch of concrete prepared for and delivered for placement on the work. The daily report shall identify when the proportions of the concrete change and the necessity for the change.

16.1.1.5. Concrete Samples: Samples shall be collected by the Contractor and shall be used to determine the slump, air content, and strength of the concrete placed on the work. One set of test beams shall be prepared for each 8-hour shift, or portion thereof, or each day of concrete production. The test beams shall be tested using the procedures in ASTM C 78 at the ages of 7 and 28 days. When the 7-day age breaks exceed the mix design strength curve the work will be accepted. When the work is accepted based upon 7-day ages the 28-day specimens do not require testing. Air content and slump shall be determined twice during each 8-hour shift of concrete production. One of the samples for air content and slump shall be when strength beams are cast.

16.1.2. Subgrade and Backfill:

16.1.2.1. Compaction Curves: A compaction curve for each of the materials shall be prepared using the procedures in ASTM D 1557. The compaction curves shall be developed in the laboratory before the compaction of surfaces in the field begins.

16.1.2.2. Field Density Testing: Field density of soil materials shall be determined using the procedures in ASTM D 1556, ASTM D 2167, or ASTM D 2937. After a calibration curve has been developed for each of the soil types, density may be determined using ASTM D 2922. The calibration curve shall be developed for each soil type by doing side by side testing. When ASTM D 2922 is used to determine density, a check of the calibration curve, doing side by side testing, shall be done at each twenty-first test point. The density of the subgrade, or backfill, shall be checked for consistency. A minimum of three test points shall be accomplished in each area of exposed subgrade. The variation of any one test from the average of all three shall not vary by more than three percent (3%).

16.1.3.

Finished Surfaces: The Contractor shall perform that testing within his responsibility which is required for each repair area. Testing shall be for smoothness and grade.

16.2.

Action Required for Deficiency Correction:

16.2.1. Aggregates Testing: When the amount retained on any one sieve size is outside the specification limits a second sample shall be taken and the test repeated. If the second sample fails, the data shall be recorded on the control chart and the frequency of the testing shall be doubled. If there is a consecutive test outside of the control limits, all of the concrete production shall be stopped and the cause of non-compliance determined. Concrete shall not be delivered for placement on the work until the cause of deficiency has been corrected.

16.2.2. Concrete Quality:

16.2.2.1. Strength: The results of the 7-day strength tests shall be plotted on a control chart. When more than one of the last five, including the current value, consecutive tests are less than the specified value; or, when the average of the last five consecutive tests, including the current value, is less than the specified value, the mixture proportions shall be changed. When the average of any five consecutive 28-day age tests are less than the specified value, the area of the placement shall be determined and the defective concrete shall be removed and replaced.

16.2.2.2. Air content: The results of testing for air content shall be plotted on a control chart. Whenever the points on the control chart approach one of the limits, adjustments of the mix proportions shall be made. When two consecutive points on the control chart fall outside the control limits, the concrete production shall be stopped and no concrete shall be delivered to the work until the deficiency has been corrected.

16.2.2.3. Slump: The results of slump testing shall be recorded on a control chart. Whenever the points on the control chart approach the control limits, adjustments shall be made in the batch weights of the fine aggregate and the water. Testing of the slump shall be made after a adjustment is made until the test results are satisfactory. Whenever the slump exceeds the upper control limit the batch of concrete shall be rejected and shall not be placed on the work.

16.2.3. Compaction Density: When a lift of soil or soil cement mixture is below the minimum specified density, the lift shall be scarified, aerated, smoothed, and compacted to the proper density.

16.3.

Reports: All results of testing shall be reported to the Contracting Officer representative within 24 hours of completion of the physical portion of the test. Each report will include the updating of the control charts. The daily reporting will not relieve the Contractor of the responsibility to immediately report, failures, equipment problems, or construction difficulties or deficiencies. Immediate reports shall be given verbally and followed up on the daily quality control reports.

END PART 3 - EXECUTION

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