|FHWA > Engineering > Pavements > Concrete > Partial-Depth Repairs|
Generic Guide Specification Partial-Depth Repairs
This work shall consist of partial-depth repairs of spalls, popouts, scaling, or other surface distress in portland cement concrete pavements. The repair area shall be prepared by removal of existing broken, damaged, or disintegrated concrete from the area indicated. Repairs shall be made with approved repair materials in accordance with this specification and with the existing pavement cross-section.
The materials used shall meet the requirements of the following AASHTO specifications:
Accelerated Strength Portland Cement Concrete Mixture
Accelerated strength shall be obtained by using Type I or Type III portland cement and calcium chloride or other accelerator to obtain a minimum strength of 3,000 psi (20.7 MPa) in 24 hours. The plastic concrete shall have an air content of 6.5 percent ± 1.5 percent. The slump shall be 1 to 3 in (50 to 150 mm) at the time of placement.
Portland Cement Concrete Mixture
The specifications of the State highway agency will apply.
Rapid Setting Repair Materials
Rapid setting repair materials shall have a minimum compressive strength of 3,000 psi (20.7 MPa) within 24 hours.
Epoxy Resin Repair Mortars
Epoxy resin repair mortars shall be prepared in accordance with the manufacturer's recommendation regarding aggregates and gradation of aggregate.
The contractor shall furnish and maintain such equipment as necessary to complete the work in accordance with the following specifications:
Areas to be repaired shall be determined by the engineer using a rod, hammer or other device to determine defective or delaminated areas. The extent of the repair area will be marked by the engineer. Areas less than 6 in (150 mm) in length and 1.5 in (35 mm) in width at the widest point shall not be repaired under this specification but shall be filled with a joint sealant material in accordance with the standard specifications.
Preparation of Partial-Depth Areas
A saw cut shall be made around the perimeter of the repair area to provide a vertical face at the edges and sufficient depth for the repair. The saw cut shall have a depth of 1 to 2 inches (25-50 mm).
Concrete within the repair area shall be broken out to a depth of 1 to 2 inches (25-50 mm) with pneumatic tools until sound and clean concrete is exposed. The maximum size pneumatic hammer shall be 30 pounds (13.5 kg).
The exposed faces of the concrete shall be sandblasted free of loose particles, oil, dust, and traces of asphalt concrete and other contaminants before placement of repair material. All sandblasting residue must be removed just prior to placement of the concrete bonding agent.
Placing Repair Material
Accelerated portland cement concrete repair mixtures
Accelerated strength PCC (3000 psi in 24 hours) repair mixtures can be used where early opening to traffic (4 to 6 hours) is required. An epoxy bonding agent is required when placing high-early-strength PCC repair for early opening to traffic. The epoxy prime coat shall be applied in a thin coating and scrubbed into the surface with a stiff bristled brush. Placement of the concrete should be delayed until the epoxy become tacky.
The repair mixture shall be placed and consolidated to eliminate essentially all voids at the interface of the repair and the existing concrete. If a partial-depth repair area abuts a working joint or crack which penetrates the full depth of the pavement, a compressible insert medium shall be used to maintain working joints or cracks. Contact between the repair and any adjacent pavement which could cause compression or other types of failure in the repair must be prevented.
Repairs should not be placed when the air or pavement temperature is below 40° F (4° C). At air temperature below 55° F (13° C), a longer cure period may be required. All repairs shall be finished to the cross section of the existing pavement. The repair shall be textured to conform to the existing pavement.
The curing compound shall be applied immediately after texturing at the rate of 150 square feet per gallon (3.7 square meters per liter).
Portland cement concrete mixtures.
Normal setting (3,000 psi (20.7 Mpa) in 3 days) PCC repair materials may be used where the repair is protected from traffic for 24 hours or more. Sand-cement grout may be used as a bonding agent. The sand-cement grout shall be composed of one part portland cement to one part sand by volume with sufficient water to produce a mortar with thick, creamy consistency. The grout shall be scrubbed evenly over the surface of the repair. Excess grout shall not be permitted to collect in pockets. The concrete repair material shall be placed before the bonding grout dries. The repair mixture shall be placed and consolidated to eliminate essentially all voids the interface between the repair and adjacent concrete. All repairs shall be finished to the cross section of the existing pavement. The repair shall be textured to conform to the existing pavement. The curing compound shall be applied immediately after texturing at the rate of 150 square feet per gallon (3.7 square meters per liter).
Rapid setting repair materials.
Rapid setting repair materials shall be installed in accordance with the manufacturer's written instructions. The preparation of the repair area surface shall be as outlined under accelerated PCC repair material except where written instructions specify otherwise. The method of bonding, placing, and curing shall be as recommended by the manufacturer. The time period recommended before opening to traffic shall also be observed.
Epoxy resin repair mortars or epoxy concrete.
Epoxy mortar and epoxy concrete mix designs shall be submitted to the laboratory for verification and approval. Those designs determined to be compatible with concrete pavement will be approved.
The epoxy resin and the catalyst shall be preconditioned before blending to produce a blended liquid that is between 75° F (24° C) and 90° F (32° C). The epoxy components shall be mixed in strict compliance with the manufacturer's mixing recommendations before aggregates are added to the mixture. The mixture shall be blended in a suitable mixer ( as specified) to produce a homogeneous mass. Only that quantity of material that is usable in one hour shall be mixed at one time. Material that has begun to generate appreciable heat shall be discarded.
The entire surface of the repair area shall be primed with neat blended epoxy immediately before the mixture is placed. Priming shall include overlapping the surface of the area adjacent to the repair. The mixture shall be placed and tamped with sufficient effort to eliminate voids and to thoroughly compact the product. The surface shall be screeded and textured to produce the required finish. The repair area shall be allowed to remain undistributed for at least 3 hours before it is subjected to traffic.
Saw cut "run-outs". The saw cut "run-outs" in the existing pavement shall be filled with the mortar of the repair material.
Portland cement concrete repairs shall not be placed when the air or pavement temperatures are below 40° F (4° C). At temperatures below 55° F (13° C), a longer cure period may be required. Insulation may be used to improve the rate of curing.
Measurement and Payment
The area measured for payment will be the number of square feet of surface area of partial-depth repair completed in placed and accepted.
Payment shall be made at the contract unit price per square foot (square meter). Such payment shall be full compensation for (a) any required sawing; (b) removing asphalt concrete repair material or spalled, broken, or damaged portland cement concrete; (c) cleaning the surface by sandblasting; (d) furnishing, placing, finishing, and curing the concrete repair; and (e) forming a new transverse and longitudinal joint, including all equipment, tool, labor and incidentals necessary to complete the work.