Effects of internal curing on the strength, drying shrinkage and freeze–thaw resistance of concrete containing recycled concrete aggregates

• Recycled fine aggregates with saturation degrees of 0%, 50% and 100% were studied.
• Effect of internal curing on recycled aggregate concrete was evaluated.
• RCA had properties comparable to that of virgin aggregate due to internal curing.

In this study, the suitability of replacing the virgin aggregate with recycled concrete aggregate (RCA) was examined under the hypothesis that the higher porosity and water absorption capacity of RCA would provide the natural moisture reservoir needed for internal curing. The concrete’s workability, compressive and split tensile strength and freeze–thaw cycle resistance and shrinkage was determined for RCA with 0%, 50% and 100% saturation. The strength increased with the saturation degree and decreased with for larger water/cement ratios and RCA contents. Using saturated or semi-saturated RCA in the concrete positively affected the durability via internal curing.