Experimental study on dynamic mechanics and energy evolution of rubber concrete under cyclic impact loading and dynamic splitting tension

Abstract

To comprehensively explore the mechanical damage and energy evolution of rubber concrete under different dynamic loading modes, the dynamic mechanical experiments of rubber concrete under four loading modes were carried out by using the split Hopkinson pressure bar (SHPB) system. The main tests were the single impact compression, cyclic impact compression with constant load, cyclic impact compression with variable load, and dynamic splitting tension based on the splitting principle of Brazilian disc (BD). The failure modes, stress waves, stress–strain curves, strength, deformation, and energy evolution characteristics of rubber concrete under different test methods were analysed. Under impact compression, the macroscopic cracks of the specimens first appeared on the local weak surface of the edge and propagated with the increase of impact pressure and impact times. Under dynamic splitting, the fracture of specimens began from the “initial compression damage zone (ICDZ)”, and extended to the center of the specimen along the force direction due to the action of stress concentration. The change of the wave impedance of the specimen determined the variation characteristics of reflected and transmitted waves, which reflected the cumulative damage evolution of the specimen in the process of cyclic impact. When the cyclic impact was carried out many times under the critical impact load, the strength and deformation showed the phenomenon of “strengthening at first and then weakening” and “decreasing at first and then increasing” respectively. The evolution curves of reflected energy ratio and absorbed energy ratio were complex and opposite. The evolution curves of specific energy absorption and absorbed energy ratio can be divided into three stages, which can effectively reflect the damage change of the specimens under different impact loads.