Integrated interface parameters of recycled aggregate concrete

•Micro properties of diverse interfaces in recycled concrete (RC) are explored.•Mechanical and durability properties of RC are weakened as RA replacements increase.•An integrated interface parameter of RC is proposed.•The rationality of the proposed interface parameter is discussed and proven.•Mechanisms of the macro inferiority of RC are quantitatively analyzed.

An integrated interface parameter of recycled aggregate concrete (RC), ξ, is proposed, based on experimental study of three RC groups with the recycled coarse aggregate (RA) replacements of 0%, 50% and 100%, respectively. Experimental study includes micro properties of diverse types of aggregate/mortar interfaces in RC, i.e., the length, width, and elastic modulus, and the macro properties of concrete materials, i.e., the compressive strength, density degree and chloride ion diffusion coefficient. The rationality of the proposed ξ is proven by the comprehensive relevant interface information and its good correlations with both RA replacement ratios and concrete macro properties, respectively. ξ-based model prediction of macro concrete properties was also found reliable. The mechanism of RC’s inferiority to natural aggregate concrete can thereby be quantitatively revealed based on ξ.