Design and Construction of a Bonded Fiber Concrete Overlay of CRCP (Louisiana, Interstate Route 10, August 1009)

The purpose of this study was to evaluate a bonded steel fiber reinforced concrete overlay on an existing 8-inch continuously reinforced concrete (CRC) pavement on Interstate 10 south of Baton Rouge, Louisiana. The project objectives were to provide an overlay with a high probability for long term success by using a concrete mix with high cement content, internal reinforcement, and with good bonding characteristics. The existing 16 year old CRC pavement had carried twice its design load and contained only a few edge punch-out failures per mile. A 4-inch concrete overlay was designed for a 20-year service life. An additional level of reinforcement-bonding was provided which utilized curb type reinforcement bars epoxied into the existing slab. The primary purpose in the additional reinforcement was to provide positive bonding at the slab edges where thin overlays have a tendency to debond due to curling and/or warping. A 9-inch tied concrete shoulder was added to increase the pavement structural capacity. The overall Serviceability Index of the pavement increased from 3.4 to 4.4 with measured Profile Index levels typically below the 5-inch per mile specification. Tests revealed excellent bond strengths and reduced edge deflections by 60% under a 22,000 lb moving single axle loading. Cores taken over transverse cracks in the overlay indicated reflection cracking from the transverse cracks in the original pavement. The final results reveal an estimated 35% of these cracks have reflected through and debonding has not occurred at the pavement edges. Anticipation of reflective cracking was one consideration in using the steel fibers which provide three-dimensional reinforcement.