Characteristics of waste concrete powders from multi-recycled coarse aggregate concrete and their effects as cement replacements

Abstract

The utilization of fine powder generated from crushing for recycling construction waste is a challenging task for the transition to zero waste and sustainable development. This study investigated the physical and chemical characteristics of recycled concrete powders (RCP) generated by repeated recycling of concrete and discussed their application as a partial replacement for cement in mortar. RCPs smaller than 0.15 mm were obtained from three different generations of multi-recycled coarse aggregate concrete, respectively, which replaced cement by 10%, 20% and 30%. The results showed that the RCP became more porous, rough and less dense with an increasing number of concrete recycling. Consequently, the properties of mortar containing RCP decreased as a function of replacement ratio and the number of concrete recycling. By reducing the replacement ratio, the properties of mortar containing RCP obtained from second-generation concrete could be comparable to those of mortar containing RCP obtained from first-generation concrete. However, for mortar made with RCP obtained from third-generation concrete, even at a 10% replacement ratio, the performance was lower than that of the previous-generation mortar with 30% RCP, indicating the need for modification for proper utilization of RCP obtained from repeatedly recycled aggregate concrete.