Mixed-mode fracture modeling of cold recycled mixture using discrete element method

Cold recycling (CR) consists of recycling asphalt pavement without the application of heat during the recycling process to produce rehabilitated pavements. Compared to other reconstruction methods, CR has advantages in energy conservation and economic saving. This paper aims to develop a three-dimensional (3D) numerical model of the Arcan test to simulate the mixed-mode cracking behavior of CR mixtures and to find the differences between CR and hot-mix asphalt (HMA) mixture. A rotatable test device was specially designed for the Arcan test to evaluate the mixed-mode cracking of specimens. A 3D numerical specimen of CR mixture was set up in the program PFC3D 4.0. A modified bilinear fracture model was established for asphalt mastic and the material parameters in the model were determined from laboratory tests. The results of virtual Arcan test verifies that three of five mixed-mode cracking simulations are reliable compared to the experimental results and 50% Mode I cracking shows the minimum error among three modes. During the cracking process of any mode, the stress concentration always occurs at the tip of cracking, and the stress value of cracking tip decreases as the cracking propagates. Compared with HMA mixtures, the emulsified CR mixture has a larger failure strain and a smaller failure stress, which can show a better anti-cracking performance in the practical engineering.