Simulation of thermal expansion mismatch at high temperature

Abstract

The thermal expansion mismatch between cement mortar and aggregate at high temperature is one of the main reasons causing the deterioration of concrete at high temperature. In this study, the thermal damage of concrete caused by the thermal expansion mismatch between aggregate and cement mortar was investigated using a meso-scale concrete model. The meso-scale concrete model is composed of mortar, aggregate and the interfacial transition zone (ITZ). Laboratory tests on the mechanical properties of cement mortar at high temperature were conducted to provide the necessary mechanical parameter for the meso-scale concrete model. The simulation results show that the particle size, content, distribution and mechanical properties of the aggregate have an effect on the thermal damage of concrete at high temperature. The smaller the particle size of concrete aggregate and the higher the elastic modulus of aggregate, the greater the damage of concrete under high temperature. Due to the increasing thermal expansion difference between aggregate and cement mortar, and the deterioration of the cement mortar with the increasing temperature, the damage of concrete increased sharply after 500 °C.