Modification of Aggregate Crack Orientation from Different Expansive Site Under Applied Stress Evaluated by Mesoscale Discrete Model

In this study, for investigating the factors affecting expansion transfer in aggregates in concrete, a numerical analysis was conducted to precisely evaluate the crack propagation from different expansive sites under applied stress. A 3D rigid body spring model (RBSM) was developed for a single aggregate particle, representing spherical aggregates. The model simulated the expansive site distribution in the aggregate. Therefore, the model could analyze the expansion behavior and crack propagation in concrete under constraint conditions. Numerical analysis results indicated that in the gel pocket model, which assumes a heterogeneous aggregate, crack generation was significantly suppressed under constraint stress. This is because the orientation of crack propagation is decided by the mesh geometry of the Voronoi element of the aggregate, and it is difficult to change the orientation of crack propagation. On the other hand, the orientation of crack propagation in the reaction rim model, where the expansive sites were uniformly formed at the aggregate surface layer, could be easily changed under constraint stress.