A multiscale model for predicting the Young’s modulus and the thermal-expansion coefficient of concrete at high temperatures
Simon Peters, Giao Vu, Günther Meschke
Abstract
A semi-analytical micromechanical model is proposed to predict the evolution of the Young’s modulus and thermal-expansion coefficient of concrete at elevated temperatures, considering three scales of observation, namely cement paste , mortar and concrete. After validation with various experimental data sets , the model quantifies different sources of damage to concrete at elevated temperatures, indicating that the chemical decomposition of cement paste has a minor influence on the evolution of the Young’s modulus, while the thermal degradation of the aggregate plays a major role. At higher temperatures, cracking is the main mechanism driving the reduction of the Young’s modulus of the investigated concretes. With regard to the thermal-expansion coefficient evaluated at multiple scales, load-induced thermal strains highly effect the homogenized total strains at the mortar level. Moreover, it is demonstrated that the dehydration degree of C-S-H increases proportionally with the measured load-induced thermal strains.