Effect of Aggregate Characteristics and Distribution on the Mechanical Characteristics of Recycled Concrete

Recycled concrete is a green material composed of natural aggregate and recycled aggregate mixed with cementing material and water in a certain ratio. The random distribution of aggregate in concrete has a great impact on material properties due to its supporting effect. In order to explore the characteristics of aggregate and the influence of its random distribution on the compressive strength performance of recycled aggregate concrete, numerical simulation is adopted in this paper. By using RAND function in ANSYS software APDL, a five-phase random aggregate model of recycled aggregate concrete was generated based on Monte Carlo method, and numerical simulation of uniaxial compression mechanical properties of concrete specimens under different recycled aggregate substitution rates (0%, 35% and 100%) was carried out. On the basis of reliability of the numerical simulation method verified by laboratory tests, multiple groups of stress–strain characteristic curves were obtained, the failure characteristics and stress characteristics of recycled concrete were analyzed, and Weibull probability statistical distribution was introduced to characterize the randomness and heterogeneity of mechanical characteristic parameters of recycled aggregate concrete. The results show that the compressive strength of recycled aggregate concrete is subject to Weibull distribution under random distribution of aggregate, and the shape coefficient m in Weibull distribution parameter can characterize the randomness and complexity of the failure of recycled concrete. The dispersion of the compressive strength of recycled aggregate concrete shows a decreasing trend with the increase in the substitution rate of recycled aggregate.