Strength Reduction Mechanism and Strength Estimation of Unsaturated Polyester Resin Concrete Deteriorated in Outdoor Soil

Abstract

The strength of unsaturated polyester resin concrete was analyzed in specimens that had spent several decades in soil outdoors and specimens subjected to hydrothermal acceleration tests. The strength reduction of both specimens was proportional to the square root of elapsed time and similar to water absorption followed Fickʼs diffusion law. In addition, the specimens regained their strength after drying. These results suggest that the main mechanism of strength reduction of resin concrete is breaking of hydrogen bonds between the resin and aggregate by water molecules, not hydrolysis of polyester resin, which is the commonly accepted theory. Furthermore, the strength of the resin concrete that had spent time in soil outdoors could be estimated using a water absorption simulation of resin concrete.