Effect of elevated temperatures and cooling methods on strength of concrete made with coarse and fine recycled concrete aggregates

In this study, the compressive and splitting tensile strengths of concrete containing both coarse and fine recycled concrete aggregates (RCA) were measured after subjected to elevated temperatures from 20 to 800 °C and two cooling regimes (natural and water cooling). Three concretes were produced with 100% coarse RCA and different replacements of fine RCA (0, 50% and 100%). Experimental results indicate that the compressive and splitting tensile strength of all concretes decline with increasing temperature irrespective of cooling methods. Concrete having 100% fine RCA content presents higher normalized residual compressive strength than concrete containing 0% and 50% fine RCA under two cooling regimes. Influence of fine RCA replacement level on normalized residual splitting tensile strength after exposure is found to be fluctuant. Data from experimental results also show that strength deterioration is more severe for concrete samples under water cooling compared to that under natural cooling, especially at temperatures of 200 and 400 °C.