Study on Dynamic Mechanical Behavior and Constitutive Model of Reactive Powder Concrete after Exposure in High Temperature

The dynamic mechanical behavior and rate constitutive model of reactive powder concrete (RPC) after exposure in high temperature are studied experimentally by means of split Hopkinson pressure bar system. Both the untreated specimens and those after exposure in high temperature (400, 600 and 800 ℃) are tested with lead flakes as pulse shapers. The experimental results show that both dynamic compressive strength and toughness of RPC after different high temperature treatments exhibit remarkable strain rate sensitivity while the peak strain and initial Young modulus do not. Furthermore, the dynamic uniaxial compressive mechanical properties of RPC at different strain rate debased after exposure at high temperature over 400 ℃. The scanning electron microscope (SEM) technology is also used to investigate the microstructure change of the RPC material; it proves that the deterioration of microstructure is the essential reason for the reduction of the RPC's macroscopic mechanical performance. In addition, ZWT viscoelastic constitutive model is utilized and modified, thus it can be used to analysis the rate constitutive relations of concrete after exposure in high temperature.