Thermal induced stress and associated cracking in cement-based composite at elevated temperatures - Part II: Thermal cracking around multiple inclusions

A 2-D mesoscopic thermoelastic damage model is developed and used to study the thermal stress field and associated fracture in a cement-based composite with multiple circular or irregular inclusions subjected to elevated temperatures. It is found that the thermal stress field and the associated cracking are dominated by (i) the thermal mismatch between the matrix and the inclusions, (ii) the arrangement of the inclusions, and (iii) the heterogeneity and the shape of the inclusions. Thermal radical cracks firstly occur between two adjacent inclusions, which have the shortest distance apart or sharp corners when the coefficient of thermal expansion of the inclusions is greater than that of the matrix. The propagation of radical cracks in the matrix will be terminated by the presence of an inclusion with higher strength at the crack tip. The numerical findings are also used to discuss the thermal cracking histories of concretes with different aggregate grading arrangements.