History
For the most part, in the United States, our transportation infrastructure was completed by the mid-1980. Many of the bridge decks were built in the 1950’s and 1960’s, have exceeded design life expectancies, and are badly in need of major repair to extend the serviceable life of these structures.
Caltrans (California Department of Transportation) Transportation Laboratories, in the 1980’s, developed a non-proprietary overlay system based on polyester resin concrete. The goal was to develop an overlay system based on an inexpensive polymer resin combined with graded aggregates. The system would be mixer-blended such that it could be paved to a fixed grade and have excellent ride qualities. It had to be rapid setting and installed within short lane closure periods since the department emphasis was to minimize urban traffic flow disruption during peak hours. Excellent adhesion to the base concrete and engineering properties consistent with excellent durability but allowing little stress development due to shrinkage or thermal changes was important. The polyester resin-based concrete overlay system developed has been in use by Caltrans since 1981. A notable example is a 1985/86, 10-lane-mile placement on the highway pavement of I-80 near Whitmore. It was placed at the 5,000 feet elevation with high-volume truck traffic and subjected to chain wear and snowplowing in the winter. Though construction practices and material deficiencies (angular rock and insufficient resin content) encountered in the 1985 portion had affected its durability, the 1986 portion performed satisfactorily. The only distress was seen at the joints of the non-reinforced jointed concrete pavement. Often the joints in the overlay were not properly cut directly over the pavement joints resulting in raveling and some spalls. The overlay was removed when the entire roadway section was rehabilitated in about 1997. Polyester concrete has been successfully used in California since 1983 for restoring and preserving bridge decks and pavements from damage by road salts and traffic wear. Excellent performance has been seen to date on most overlays installed. FHWA has routinely accepted polyester concrete overlays in California as a non-experimental overlay material since 1988. Based on this successful history, Caltrans has specified and installed polyester concrete overlays on several major San Francisco Bay area bridge structures.