Influence of heterogeneity on strength and failure characterization of cement-based composite subjected to uniform thermal loading

摘要

The influence of heterogeneity on strength and failure characterization of cement-based composite subjected to uniform thermal loading is investigated by Material Failure Process Analysis code (MFPA). The results indicate that failure patterns greatly depend on the location of cracks initiation, which is found to be sensitive to the local disorder nature within the specimen. The cracks initiation, nucleation and propagation at mesoscopic level show that it is very difficult to predict where the macrocrack will begin in the relatively homogeneous specimen. However, more randomly failures occur in the relatively heterogeneous specimen at the early stage of temperature elevation. And the macrocrack nucleation starts well before the peak strength is reached which indicates that the crack propagation and coalescence can be traced and be used to predict the macrofracture of the specimen. The failure processes of concrete indicate that most of cracks occurred at first on the interface between mortar matrix and coarse aggregates due to thermal mismatch, and then propagate into the mortar matrix, even break down the coarse aggregates.