Physical and mechanical properties of quaternary blended concrete with recycled coarse aggregates and crushed waste glass

Abstract

Research into using recycled coarse aggregates (RCA) and crushed waste glass (CWG) has been on the rise as there is a strong push towards achieving sustainability in the construction industry. However, only limited studies have been reported with respect to utilising low cement binder system in conjunction with RCA and CWG as coarse and fine aggregate replacement respectively. This study developed a new low cement (30%) quaternary binder system using supplementary cementitious materials consisting of ground granulated blast furnace slag, fly ash and silica fume to mix with RCA and CWG. Replacement ratio of RCA was at 30%, 50% and 100% by volume using modified triple mix method. CWG, with replacement volume of 20% and 40% for fine aggregates, were added to mixes containing 100% RCA. The developed composites were examined with respect to their physical and mechanical properties. Scanning electron microscopic and energy dispersive X-ray were also carried out to provide better understanding at microstructure level. Results indicated that the addition of RCA had influences on workability and composite density whilst leading to reduction on compressive, splitting tensile, flexural strength and static elastic modulus. Addition of CWG reduced workability, density and compressive strength but did not significantly alter the splitting tensile and flexural strength. Existing correlations in literature for predicting the mechanical properties were compared and new empirical formulae were developed based on the experimental results. The findings of this study indicate that 50% RCA replacement of natural coarse aggregates together with the modified triple mix method and low cement binder can be used to make green concrete satisfying the structural application purposes.