Use of fresh properties to predict mechanical properties of sustainable concrete incorporating recycled concrete aggregate

Recycled aggregate concrete (RAC) is not widely used in construction because of the concerns related to its quality. This paper investigates the effect of the replacement levels of recycled concrete aggregate (RCA) on bulk and hardened densities of RAC. The analysis of variance (ANOVA) was used to investigate the sensitivity of bulk and hardened densities of concrete to the replacement level of RCA. Predictive equations were developed to estimate the 3-day, 7-day, and 28-day compressive strength of RAC from its fresh properties, which are helpful for early quality control inspection of RAC. Furthermore, a predictive equation has been proposed to determine the flexural strength of RAC based on its 28-day compressive strength. The comparison of the predictive capability of the proposed and widely used code equations showed the incapability of the latter to estimate the flexural strength of RAC. In contrast, the proposed equation demonstrated a high level of prediction accuracy.