Mesoscale studies on the effect of aggregate shape idealisation in concrete

Abstract

Mechanical properties of concrete, such as strength, stiffness and its damage characteristics, are found to depend significantly on the properties of constituent materials. However, this dependency is rarely taken into consideration in the prediction of material response to mechanical loads. Instead, the most generally sought alternative for prediction of material response involves conducting laboratory tests. A mesoscale model that incorporates the properties of the mesostructure and its influence on mechanical response is adopted. Mesoscale models of concrete contain coarse aggregates, cement mortar and, optionally, an interfacial transition zone. An aggregate shape idealisation scheme is determined numerically to generate a circular aggregate mesoscale model by carrying out numerical simulations under uniaxial compression and tensile conditions. The numerical procedure followed in the present mesoscale simulations is validated with the available experimental data. The circular aggregate model is generated by idealising the actual irregular aggregate to a circular one using: (a) an area-equivalence approach and (b) a circumference-equivalence approach. To assess the effective idealisation scheme under static loading conditions, aspects such as strength, stiffness and damage distribution are considered. Simulation results show that the circumference-based model provides higher compressive strength and stiffness and lower tensile strength than the area-based model.