The effect of curing conditions on the compressive strength of recycled aggregate concrete

• We studied the effect of curing on the recycled aggregate concrete.
• We used 2 qualities of recycled aggregate with 4 different percentages of replacement.
• Open-air curing was compared with a standard and controlled curing environment.
• The recycled aggregate specimens lost up the 20% of their strength at open-air.
• The specimens gave good strength results when they were cured at standard conditions.

This work assesses the influence of different curing conditions on the compressive strength of recycled aggregate concrete. Two different qualities of recycled aggregate were used to make concrete with 0.65 water/cement rate. The recycled aggregates were added with their natural moisture and they replaced different percentages of the coarse aggregate (0%, 20%, 50% and 100%).The concrete specimens were exposed to two different environments (standard curing and open-air curing) for 28 days. The results showed that the 7-days strength increases with the percentage of replacement, being this behavior more evident for the standard curing environment. The 28-days compressive strengths of concretes with recycled aggregates were found similar to the ones obtained with natural aggregate when the standard curing environment was considered. However, the recycled aggregate concrete specimens lost up to the 20% of their compressive strength when they were cured in open-air conditions. This made evident the effect of the curing conditions on the resistance of recycled aggregate concrete.