Properties of green mortar blended with waste concrete-brick powder at various components, replacement ratios and particle sizes

Abstract

Concrete and brick waste sourced from construction waste are commonly mixed together, and grinding such concrete and brick waste mixtures directly into waste concrete-brick powder (WCBP) as an alternative binder is sustainable and promising. This study investigated the micro- and macro-properties of green mortar containing various WCBPs. The results show that WCBP consisting of waste concrete powder and waste brick powder has certain pozzolanic activity and good filler effect in new cement-based materials, and the waste brick powder has superior activity to the waste concrete powder in WCBP. The mix of WCBP decreases the fluidity and prolongs the setting time of fresh mixture. Incorporating waste brick powder refines the pore size of paste, but the mixed waste concrete powder enlarges the pore size of paste; moreover, the pore size of paste with fine particle WCBP is superior to that of paste with coarse particle WCBP. The mechanical strength and water absorption resistance of mortar generally decreases with WCBP addition, and there exists a linear relationship between the WCBP replacement level and strength of WCBP mortar. At the fixed WCBP replacement ratio, the mechanical strength and water absorption resistance of WCBP mortar are improved as the proportion of waste brick powder content in WCBP increases. Particularly, decreasing the particle size of WCBP improves the mechanical strength and water absorption resistance of WCBP mortar. Optimizing the WCBP component, replacement ratio and particle size can prepare WCBP mortar with satisfactory properties.