Thermal expansion prediction of cement concrete based on a 3D micromechanical model considering interfacial transition zone

Thermal expansion of concrete is a main factor of concrete failures especially in underground waterproof engineering, overlong structural engineering and mass concrete construction. Thus, the coefficient of thermal expansion (CTE) of concrete is an important parameter to be determined. A micromechanical model, namely the 3D Two-Layer Built-in Model is developed to obtain the overall CTE of cement concrete. The existence of interfacial transition zone (ITZ) between aggregate and cement paste is considered in the model, and the ITZ model is simplified as a spring layer with a certain stiffness k. According to the existing testing data of three types of cement concrete whose aggregates are siliceous river gravel (RG), dolomitic limestone (DL) and granite (GR) respectively, the CTEs of prediction model are obtained and validated by the measured values. Moreover, the effects of interface, water cement ratio, volume fraction ratio of fine aggregate to coarse aggregate, air voids, CTE of coarse aggregate and elastic modulus of cement paste on the CTE are analyzed.