Three-dimensional mesoscopic investigation of the compression mechanical properties of ultra-high performance concrete containing coarse aggregates

To better understand the damage characteristics of ultra-high performance concrete (UHPC) containing coarse aggregates (CA) under load effects, we proposed a novel three-dimensional (3D) packing model, considering the random distributions of CA and steel fibers. Based on the packing model, a 3D mesoscale model was developed to simulate the quasi-static compression properties of UHPC. The model assumes UHPC to be a four-phase composite, including the homogeneous mortar matrix, CA, interfacial transition zones, and steel fibers. In addition, we numerically studied the failure characteristics of UHPC specimens with different mix proportions (CA without fibers; fibers without CA; and both CA and fibers). The results of the simulation and experiment were in agreement with each other, thus manifesting that the proposed 3D packing modelling approach and mesoscopic model can be effectively used to investigate the mechanical behaviors of UHPC.