Grading Method of Mixed Recycled Coarse Aggregate

Due to the limitations of sorting technology, mixed recycled coarse aggregate, which mainly includes recycled concrete coarse aggregate and recycled brick coarse aggregate, accounts for a large proportion of recycled aggregate. This paper proposes a grading method for mixed recycled coarse aggregate to ensure satisfactory concrete performance. Distribution of specific density, saturated surface dry density, water absorption, and crushing value of mixed recycled coarse aggregate, as well as the effect of recycled brick coarse aggregate content, on the four parameters of mixed recycled coarse aggregate are investigated in this paper. The water absorption and crushing value were selected as the main grading indexes of mixed recycled coarse aggregate by using the weighted grey analysis method. According to the analysis results of the nonlinear fitting curves between the property indexes of mixed recycled coarse aggregate (water absorption and crushing value) and the performance parameters of mixed recycled coarse aggregate concretes (cubic compressive strength, prism compressive strength, splitting tensile strength, static modulus of elasticity, and the flexural strength), the mixed recycled coarse aggregates were divided into two categories; Categories I and II are used for structure and nonstructure uses, respectively.