03320 Portland Concrete Cement_ Full Depth Rpr.doc

Base Pavements IDIQ

JCGU 09-1700

DIVISION 03 - CONCRETE

SECTION 03320 - FULL-DEPTH REPAIR OF EXISTING CONCRETE PAVEMENT

PART 1 – GENERAL:

1.1 REFERENCES: The publications listed below form a part of this specification. The publications are referred to in the text by basic designation only, and shall be the latest edition in effect on the date of solicitation except where a date is given.

American Society for Testing and Materials (ASTM)

ASTM C 494

Chemical Admixtures for Concrete

ASTM E 488

Strength of Anchors in Concrete and Masonry Elements

Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges, Texas Department of Transportation, June 2004.

1.2 SUBMITTALS:

The following shall be submitted in accordance with Specification SECTION 01010:

Test Reports:

Copies of all test reports for tests specified in paragraphs "Concrete" and "Field Quality Control" shall be submitted within 24 hours of the completion of the test.

Records:

Copies of certified delivery tickets for all concrete used in the construction shall be submitted.

PART 2 – PRODUCTS:

2.1 MATERIALS:

2.1.2 Hydraulic Concrete: Provide materials that meet the pertinent requirements of following TXDOT, Item 360 “Concrete Pavement” and Item 421, “Hydraulic Cement Concrete”. The coarse aggregate shall be either Grade 2 or 3. Air entrainment will be required. An air entrained content of three (3) to six (6) percent shall be provided. The fine aggregate shall be Grade 1 with a fineness modulus of 2.60 to 2.80. The concrete shall be designed to include seven (7) sacks of Type III cement. The maximum water cement ratio shall not exceed 5.5 gallons per sack. An ASTM C 494 Type A water-reducing admixture and ASTM C 494 Type C nonchloride set-accelerating admixture may be required at the job site when the temperature of the concrete is above 55 degrees F. The concrete will be designed to achieve a minimum flexural strength of 425 psi in 24 hours.

2.1.3 Reinforcing steel: Reinforcing steel and dowels shall be of the size and grade indicated on the plans and shall conform to TXDOT, Item 440, “Reinforcing Steel” and the requirements of Specification SECTION 03200.

2.1.4 Stabilized Base Material: Stabilized base material shall conform to the material requirements of Specification SECTION 02241 - Stabilized-Aggregate Base Course.

2.1.5 Epoxy: Epoxy shall conform to the requirements of TXDOT, Item 780, "Epoxy Injection".

PART 3 – EXECUTION:

3.1 PATCHES:

3.1.1 Patches shall be a minimum of six (6) feet in length and the full lane in width. If the area to be repaired is covered with asphaltic concrete, the asphaltic concrete shall be removed over an area sufficient to allow for proper repair of the concrete pavement.

3.1.2 A pressure relief groove approximately 2 inches deep shall be sawed transversely 6 inches (to the inside) from the patch ends. Full-depth saw cuts shall be made transversely along the patch ends.

Longitudinal saw cuts shall be full depth along the patch sides. If spalling occurs along the full-depth longitudinal saw cut, the longitudinal saw cutting shall then include a longitudinal 2-inch deep pressure relief groove and be performed in the same manner as the transverse saw cutting. Additional full-depth saw cuts may be made as needed to facilitate removal of the concrete within the limits of the required full-depth cuts. Concrete adjacent to the patch shall not be spalled or fractured by the removal procedure.

3.1.3 The concrete shall be removed, taking care not to disturb the underlying pavement support. The total lift-out method shall be used within the limits of the full-depth saw cuts.

3.1.4 All loose subbase material shall be removed and replaced with stabilized base material as specified in Specification SECTION 02241 - Stabilized-Aggregate Base Course. If concrete is used to replace loose subbase material, a bond breaker such as a polyethylene sheet shall be used at the interface between the replaced subbase material and new concrete pavement. The Contractor shall schedule his work so that the concrete placement will follow the full-depth saw cut by no more than seven (7) days. Dowel bars and reinforcing bars shall be replaced with new bars of the same size, grade and spacing. Dowel bars will be required. New reinforcing bars shall be placed and firmly supported by approved bar chairs.

3.1.5 For all concrete pavement, the following procedure of reinforcement shall apply:

3.1.5.1 The longitudinal tiebars shall be reinforcing steel as detailed on the plans. The depth of reinforcing steel into the patch area shall be 30 bar diameters. The depth of the reinforcing steel into the existing concrete shall be based on the pull-out test for bond strength but no less than 12 inches. The longitudinal tiebars shall be epoxy grouted in the existing concrete.

3.1.5.2 Transverse tiebars shall be as shown on the drawings and shall be epoxy grouted, with the same gout as used for the longitudinal tiebars, into the existing concrete pavement to a depth of 12 inches. Tiebar spacing shall be as existing pavement. Other reinforcing steel for the repair shall match the existing reinforcing steel.

3.1.5.3 The Contractor must demonstrate, through simulated job conditions, that the bond strength of the longitudinal and transverse tiebars (for continuity of the reinforcing steel) shall withstand a tensile load in the field of 3/4 of the yield strength of the tiebar by using a tension test required by ASTM E 488. This test shall be conducted within 18 hours after grouting of the tiebar into existing concrete. The Contractor shall demonstrate this test before patching work can begin. Concrete placement shall not begin in a given patch until the tiebar and dowel-bar grout has attained sufficient strength to preclude displacement of the tiebars by the concrete. Grout retention disks shall be used when required. Immediately prior to placing the concrete, the subbase and each face of existing concrete shall be wetted. Approved hand manipulated mechanical vibrators shall be used to induce the proper consolidation of the concrete. The concrete shall be screeded to the elevation of the adjacent concrete pavement and checked with a straightedge to insure that the riding surface will be satisfactory. The concrete shall be given a broom finish. The concrete shall be cured for a period of not less than 72 hours from the beginning of curing operations. All exposed surfaces, including vertical surfaces of the placed concrete, shall be cured immediately after finishing operations have been completed. The applied curing material may be removed as necessary to saw joints or to comply with the requirements for any surface test. The hardened concrete surface shall be maintained wet with a water spray, if required, and the curing material replaced immediately after completion of sawing, testing and any required surface correction. Failure to maintain adequate curing shall be cause for immediate suspension of operations.

3.1.5.4 The repaired area may be opened to traffic when the concrete has cured for 24 hours.

END OF SECTION

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