Microcrack Propagation Study of Concrete under Compression

Abstract

The propagation of microcracks in concrete under compression is studied by the finite element method. To this end, concrete is modeled as a two‐phase composite, consisting of a mortar matrix and aggregate inclusions. Two distinct types of microcrack (mortar crack and bond crack) are considered. To reflect the current stage of development, the principle of nonlinear fracture mechanics and the joint finite elements coupled with the generalized plasticity concept are incorporated into the present analyses. The numerical results thus obtained indicate that the stress state has a very significant influence on the development of mortar cracks; much less influence on the propagation of bond cracks is seen. Combined with well‐known experimental results then, the present study concludes that the deformation of a concrete specimen before peak load should be more uniform than its postpeak deformation and that the hardening behavior of a concrete specimen should be less influenced by loading conditions than the softening behavior. These conclusions provide an explanation of the cause of the characteristic observed behavior of concrete.