3D mesoscopic analysis on the compressive behavior of coral aggregate concrete accounting for coarse aggregate volume and maximum aggregate size

For better understanding the compressive behavior of coral aggregate concrete (CAC) with different volume fractions and maximum aggregate sizes (MASs) for coarse aggregate, an all-sided mesoscopic investigation was performed using a novel 3D mesoscale model assuming concrete to be a three-phase composite material composed of coarse aggregate, mortar matrix and interfacial transition zone. The random characteristics of coarse aggregate in shape and spatial distribution were considered adequately in the mesoscale model. Fourteen types of cubic mesoscale models (sized by 100 × 100 × 100 mm3) with various aggregate volume fractions (0–67.4%) and MASs (10–30 mm), were established to study the quasi-static compressive behaviors of CAC, such as the deformation processes, failure patterns and stress–strain relations. By comparing the simulation results and the available test results, it has proven to be that the present 3D mesoscale modelling approach was capable of simulating and investigating the compressive behavior of CAC. Besides, it was indicated from the simulation results that the compressive strength of CAC generally decreases with the increase of MAS, but when the MAS exceeds the critical value, the varying trend of compressive strength tends to slow down. Additionally, the compressive strength tends to decrease before reaching a certain aggregate volume, but when it exceeds a certain volume, that is, the optimum aggregate volume, the compressive strength exhibits a rebounding trend. And the optimum aggregate volume of CAC with the MAS of 20 mm was determined from 58.0% to 61.1%. Furthermore, a regressive relation between concrete strength and aggregate volume was preliminarily derived from simulation and available test results, which can provide some enlightenments for the mix design and performance prediction of CAC.