Analytical and Model Studies on Behavior of Rigid Polyurethane Composite Aggregate under Compression

To determine the mechanical behavior of rigid polyurethane composite aggregate (RPC) in compression, uniaxial compressive tests of RPC specimens, which were molded by reaction injection, were conducted under different specimen densities. The failure behavior of the specimens was observed by macroscopic compression tests and microscopic scanning electron microscope (SEM) tests. Based on the classical mechanical constitutive model of ordinary concrete and RPC uniaxial compression tests results, a three-stage model considering specimen's density was proposed to describe the RPC's mechanical behavior. Although this model is more suitable for single-sized RPC, a mechanical theoretical model that is suitable for different grades of RPC was proposed based on damage mechanics theory. The three-stage model has fewer parameters and higher accuracy for single-sized RPC's stress-strain curves than does the mechanical theoretical model. The latter model is suitable not only for single-sized RPC but also for different grades of RPC.