Dynamic tensile properties and fracture behaviors of coral aggregate concrete

Abstract

As an alternative building material, the feasibility of coral aggregate concrete has been widely recognized for the engineering construction on reef islands. To explore the tensile properties and fracture behaviors of coral aggregate concrete, the splitting tension tests were conducted utilizing an MTS testing machine and a split Hopkinson pressure bar (SHPB) device. The changes in tensile strength and failure strain, energy dissipation, and failure pattern of coral aggregate concrete with respect to strain rate were systematically analyzed. The results show that the dynamic tensile strength of coral aggregate concrete is more dependent on the loading strain rate than conventional concrete and cement mortar. The tensile failure strain increases nonlinearly with an increase in strain rate and tends to an upper limit. Likewise, the energy absorption increases with increasing strain rate, which is mainly consumed by generating more fracture planes leading to more damage and fragmentations of coral aggregate concrete. And the splitting tensile fracture always penetrates directly through the coral aggregates. Furthermore, a real mesostructure concrete modelling was developed to characterize the fracture behaviors of coral aggregate concrete. The node-split method and damage failure method were combined to effectively capture the crack and fracture process. The mesoscopic simulation elucidated the influence of the low-strength large coral aggregate and porous mortar matrix on the dynamic fracture behaviors. Lastly, a strength-ratio-based approach for brittleness analysis indicates the brittleness of coral aggregate concrete is less than that of conventional concrete with approximate strength grade under dynamic loading.