Study of three-dimensional concrete shrinkage crack behavior using a mesoscale concrete model with actual geometry and random aggregate

Combining a laser scanning test and a triangular mesh folding algorithm, a 3D aggregate database based on actual aggregate shape was generated. An indirect delivery method of the actual aggregate based on a fitting cuboid was proposed. A mesh-scale numerical analysis model of concrete shrinkage cracking behavior in a dry environment was established. The spatial distribution of the concrete moisture field was determined using wet diffusion simulation, and the damage distribution of the concrete was calculated according to the change in humidity field. The simulation results agreed well with the experimental results, verifying the feasibility of the model. Based on this, the propagation mechanism of concrete dry shrinkage cracks in a dry environment was studied, and the internal relationship between the development law of concrete surface dry shrinkage cracks and mesoscopic media was revealed. Results show that the edge of the concrete cube loses water faster than the surface, and the initial crack is more likely to occur at the edge. In addition, the initial cracks and surface damage points occur on the surface of the aggregate and are affected by the aggregate particle size and the distance from the surface. Furthermore, as ambient relative humidity decreases, the development depth of the surface cracks increases continuously, and more penetration cracks and damage points appear on the concrete surface, showing a crack network with the aggregate as a node. © 2022 Chinese Academy of Sciences. All rights reserved.