Section 561 — Concrete Crack Repair By Epoxy Injection

Description

561.01This work consists of repairing cracks in concrete by injecting epoxy into the cracks.

Material

561.02Conform to the following Subsections: Epoxy resin adhesives 725.12 Latex -modified mortar 701.05(c)

Construction Requirements

561.03General. At least 14 days before starting concrete crack repair work , submit the following according to Subsection 104.06:

(a)Person nel qualifications;

(b)Manufacturer’s SDS and product data sheets;

(c)Manufacturer’s installation recommendations; and

(d)Work plan for performing the work. Conduct a pre -injection preparatory phase meeting at least 7 days before the start of injection operations according to Subsection 153.06(a) .

561.04Crack Preparation . Identify work areas and mark the cracks to be repaired for approval. Prepare cracks according to the manufacturer’s recommendations. Remove dirt, laitance, and other debris from the exterior and interior of the crack. Apply a temporary surface seal material with sufficient strength and adhesion to confine the inje cted epoxy resin adhesive within the crack until cured. Provide openings (entry ports) in the surface seal along the crack. Make the distance between entry ports at least the thickness of the concrete member being repaired.

561.05Injection Procedure. Maintain the epoxy resin adhesive component mix ratio within 5 percent by volume as recommended by the manufacturer. Do not use solvents to thin the epoxy. Use positive inline displacement type equipment to meter, mix, and inject the epoxy at pressures no mor e than 200 pounds per square inch. Inject epoxy into cracks according to the manufacturer’s recommendations until the entire crack is filled. Perform the following tests for each injection unit at the start and at the end of each day.

(a)Ratio check test. Disconnect the mixing head of the injection equipment. Pump the two adhesive components through a ratio check device having two independent valved nozzles that can control the flow rate and back pressure by opening or closing the valves. Use a pressure gauge that can sense back pressure behind each valve. Adjust the discharge pressure to 200 pounds per square inch for both epoxy components. Simultaneously discharge both epoxy components into separate calibrated containers. Compare the discharged quantities to determine the mix ratio. After the test is completed at 200 pounds per square inch discharge pressure, repeat the procedures for 0 pounds per square inch discharge pressure.

(b)Pressure check test. Disconnect the mixing head of the injection equipment. Attach the two adhesive component delivery lines to a pressure check device having two independent valved nozzles that can control the flow rate and pressure by opening or closing the valves. Use a pressure gauge that can sense the pressure build -up behind ea ch valve. Close the valves on the pressure -check device and operate the equipment until the gauge pressure on each line reads 200 pounds per square inch. Stop the pumps and check that the gauge pressure does not drop below 190 pounds per square inch within 3 minutes.

(c)Records. Maintain and make available complete and accurate records of the ratio and pressure check tests. Additional ratio and pressure check tests may be required.

561.06Coring. Take one 2 -inch diameter test core according to AASHTO T 24 for every 50 feet of repaired crack at designated locations. The crack repair is acceptable when the epoxy bonding has penetrated at least 90 percent of the crack volume within the core sample. If a test core is unacceptable, redo that 50 -foot crack segment or the segment that the core represents and resample. Repeat this procedure until acceptable crack repair is achieved.

561.07Finishing. Remove the surface seal and fill sample core holes with polymer concrete and mortar according to the manufacturer’s rec ommendations . Finish the face of the crack, the entry ports, and the core holes flush with the adjacent surface and finish the surface to match the adjacent concrete.

561.08Opening to Traffic. Do not allow traffic on crack injection work for 6 hours afte r completion of the crack injection work or until the injected epoxy resin has attained a compressive strength of at least 1450 pounds per square inch, whichever is less. For bridge deck repairs, stage traffic so that the edge of the nearest travel lane to the repair area is no closer than the center of the adjacent girder.

561.09Acceptance. See Table 561-1 for sampling, testing, and acceptance requirements. Material for concrete crack repair will be evaluated under Subsections 106.02 and 106.03. Concrete crack repair work will be evaluated under Subsections 106.02 and 106.04.

Measurement

561.10Measure the Section 561 pay items listed in the bid schedule according to Subsection 109.02 .

Payment

561.11The accepted quantities will be paid at the contract price per unit of measurement for the Section 561 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 561-1 Sampling, Testing, and Acceptance Requirements

Material or

Product Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Daily Start -up & Shutdown Testing

Epoxy resin

adhesive Process control (153.03) Ratio check (Mix) − Subsection

561.05(a) Daily before starting work & after ending work Injection unit No Subsection 561.05

Pressure

check − Subsection 561.05(b) " " " "

Production

Epoxy resin

adhesive Measured & tested for conformance (106.04 ) Penetration of material into crack − Subsection

561.061 core for every 50 ft of repaired crack length In-place after epoxy resin injection completed No Upon completion of test