Abstract: In an attempt to understand the influence of recycled coarse aggregate on the properties of recycled concrete subjected to sulphate erosion, we probed into the changes in mass loss rate, elongation rate, relative dynamic elastic modulus, and sulfate ion diffusion depth of recycled concrete under the combined actions of drying-wetting cycles and sulphate erosion. Research findings demonstrated that the mass loss rate of recycled concrete with 100% recycled coarse aggregate was the largest, reaching 0.35%. The decline of relative dynamic elastic modulus can be divided into three stages: uniform decline stage, slow transition stage, and accelerated falling stage. The elongation of the specimen increased gradually with the increase of erosion age, and such increment accelerated. During the test, sulfate ions gradually diffused into the specimen, and as the content of recycled coarse aggregate increased, the erosion damage became faster and more apparent.The research findings offer reference for determining the dosage of recycled coarse aggregate in practical engineering.

Key words: recycled concrete, replacement rate of recycled coarse aggregate, drying-wetting cycle, durability, sulfate erosion