DELAMINATION IN BONDED CONCRETE OVERLAYS OF CONTINUOUSLY REINFORCED PAVEMENT

Abstract

The Texas State Department of Highways and Public Transportation (SDHPT) has placed over 25 lane miles of bonded concrete overlay (BCO) in the Houston area. Following the successful construction of a 1,000 foot test section in 1983, the SDHPT overlaid approximately 3.2 miles of an eight lane freeway. Debonding of some areas were reported within one year of completion. After debonding was discovered early in 1987, a study was initiated to determine the location, extent and cause of the delaminations. Furthermore, the investigation was to determine if debonding was a progressive phenomenon. Several techniques were used to characterize the extent of debonding. For the conditions in Houston, manual sounding of the overlay followed by video tape recording of the pavement yielded the most practical and economical survey results. The use of ground penetrating radar to locate delaminated area was found to be inappropriate for the conditions presented in Houston. When assessing the development of delamination with time, operator variance in sounding and seasonal effects have a pronounced influence on the evaluation. The survey results showed the use of portland cement grout as a bonding agent reduces the chance of debonding under conditions present in Houston. Also, the use of steel fiber reinforcement with siliceous river gravel or crushed limestone aggregate with welded wire fabric reduces the likelihood of delamination when compared to siliceous river gravel and welded wire fabric.