As a green building material, recycled aggregate is widely used in the construction market. However, the defects of high water absorption, high pressure crushing value, surface micro cracks, and irregular morphological characteristics of recycled aggregate limit the recycling of recycled aggregate. Therefore, the influence of recycled aggregate morphology on its mechanical properties were studies in this paper. Based on the uniaxial compression test, the discrete element numerical simulation method was adopted to establish mathematical models of recycled aggregate concrete under disc shape, regular triangle, regular quadrilateral, and regular pentagon aggregate at the same position with the same compactness, particle size, and particle size volume proportion, and the mesoscopic parameters through comparison and analysis with laboratory test results were determined. The mechanical response curve and fracture mode of recycled aggregate concrete under uniaxial compression were obtained. At the same time, the relationship between the roundness and the peak stress of recycled aggregate concrete was analyzed by introducing the aggregate morphology parameter (roundness), and the roundness model formula was proposed to predict the strength, and the comparison analysis was made with the test results to verify its feasibility. The results show that the aggregate morphology affects the crack propagation law. The crack distribution is more dispersed with the aggregate angle. There are different degrees of bond failure and debris formation at the crack zone. The aggregate morphology affects the strength of the model specimen, and the power index of the peak stress decreases with the aggregate roundness. The strength of recycled aggregate concrete can be accurately predicted according to the roundness model formula. The previous research can provide valuable reference for optimizing the design of recycled aggregate concrete.
Li et al. (Sat,) studied this question.