Compressive and flexural strengths of recycled aggregate concrete: Effect of different contents of metakaolin

Abstract

This paper experimentally investigates the workability and mechanical performance of recycled aggregate concrete (RAC). It evaluates the influence of using metakaolin (MK) as cement replacement material on the performance of RAC. The cement was replaced with MK at three contents (10%, 20% and 30%). In total, five mixes were prepared. Three mixes of RAC made with these 3 contents of MK, one RAC mix was made without MK and one mix was made with natural coarse aggregate (NCA) for comparison reasons. It was determined that RAC reduces the workability and mechanical performance properties concrete. The results of the mixes including MK reveal that MK negatively affects the workability of concrete. Nevertheless, MK has the potential to enhance the mechanical properties of RAC. If cement is replaced with MK at content up to 20% of cement mass, similar compressive and flexural strengths to that of NAC can be achieved.