Mesoscale simulation on thermal cracking in concrete by using a coupled thermal–mechanical lattice Boltzmann-Peridynamic model

Abstract

Previous numerical models of thermal cracking in concrete often neglect the thermal exchange between crack surfaces and the surrounding air. Besides, they often face difficulties in accurately quantifying the crack width and length. This paper proposes a coupled thermal–mechanical Lattice Boltzmann-Peridynamic (LB-PD) model to simulate the thermal cracking in concrete on a mesoscopic scale. A generation-placement method is used to construct the concrete mesostructures. The thermal cracking process in concrete on mesoscale is modeled across multiple scales by adjusting the Lattice Boltzmann (LB) particle distribution function and defining various types of Peridynamic (PD) bonds. Thermal exchange effects at crack surfaces is dynamically captured through the real-time identification of these surfaces during the LB particle streaming process. Additionally, a multi-rate time integration method is applied to numerically solve the thermal–mechanical coupling process. The Zhang-Suen thinning algorithm is employed to extract the crack skeleton, enabling quantitative measurements of crack width and length. The accuracy of model is validated by comparing it with analytical solutions and experimental data. Finally, the effects of thermal source temperatures, thermal exchange on crack surfaces, and different aggregate volume fractions on the coupled evolution of thermal cracks and temperature are investigated by using the proposed model. Numerical simulations demonstrate that thermal exchange on crack surfaces further promotes crack propagation by enhancing temperature diffusion. In contrast, concrete with a higher aggregate content exhibits slower development of internal thermal cracks.