Low Temperature Crack Propagation and Evolution of Asphalt Mixture

Three typical structure asphalt mixtures, such as suspend‑dense structure, skeleton‑dense structure and coarse‑aggregate‑skeleton structure, were used as test subjects to analyze the influence of crack propagation from a macro prespective through the indirect tensile test(IDT). Combined with the numerical analysis, heterogeneous discrete element models for asphalt mixtures were established by the random particle‑based growth algorithm. The crack evolution characteristics of three asphalt mixtures under low temperature were analyzed through four aspects: the change in the number and proportion of micro cracks, the energy release rate, and crack tip stress field. The results indicate that in terms of the time‑domain variation of the crack energy release rate G(t), as changes of the spatial distribution of the aggregate in the coarse‑aggregate‑skeleton, skeleton‑dense and suspend‑dense asphalt mixture, the internal energy consumption rate increases, while the energy storage rate reduces, and thus increasing the total crack energy release rate. It indicates that more energy is required when the suspend‑dense asphalt mixture is fractured. In terms of the stress field distribution in the crack tip region, compared with the coarse‑aggregate‑skeleton and skeleton‑dense asphalt mixture, the interior of suspend‑dense asphalt mixture is less likely to appear the phenomenon of stress concentration, which is beneficial to suppress the occurrence of shear stress field, thereby reducing the number of mode Ⅱ cracks. © 2022, Editorial Department of Journal of Building Materials. All right reserved.