Numerical study of shrinkage cracking in concrete and concrete repair systems

The shrinkage cracking processes in a cement-based composite, which include crack initiation, propagation and coalescence, as well as diffusion-damage coupling, are numerically studied using a mesomechanical numerical model to better understand the shrinkage cracking growth mechanisms and the effects of cracks on moisture diffusion. This study analyzes the shrinkage crack initiation and growth processes in a repair layer of mortar, which is cast on the top of an old concrete substrate and initially saturated with water. The potential shrinkage crack development is driven by the associated drying process. The results illustrate the fracture infilling, saturation and delamination processes in the concrete repair system by decreasing the bond strength between the repair mortar and the substrate from 4 to 1 MPa. Large concrete repair system bond strengths cause cracks to initiate on the surface of the repaired mortar and propagate to the interface. However, debonding is observed at lower bond strengths. The numerical model is shown to be a viable tool for damage analyses under both mechanical loads and hygral gradients.