Optimized application of ternary brick, ceramic and concrete wastes in sustainable high strength geopolymers

Abstract

This study considered the use of recycled clay brick (RCB), recycled ceramic wall tile (RWT) and recycled concrete (RCW) wastes to develop an optimized ternary geopolymer system at ambient environment. The ternary geopolymers (BTC) were designed comprising between 20 and 80% of RBW, RCT and RCW precursors, while targeting different values of SiO2/Al2O3 and Na2O/SiO2 at a constant liquid-to-solid (L/S) ratio. The correlation between the design factors and the fresh and mechanical properties including flowability, setting time, compressive strength and microstructure was comprehensively investigated. Further improvement of ternary compositions was explored by integrating up to 45% metakaolin (MK), ground granulated slag (GGBS), Class C fly ash (F–C) and Class F fly ash (F–F) into designed BTC precursors. In addition, the effect of initial curing temperatures of 50 °C, 75 °C, and 100 °C was evaluated based on the optimized BTC combinations. The use of a ternary composition of 20%RCB:40%RWT:40%RCW at SiO2/Al2O3 of 10.2 and Na2O/SiO2 of 0.18 allowed to achieve high strengths at ambient conditions. This composition was further optimized with the incorporation of GGBS that yielded greater amorphous phase formations and maximum strength enhancements. Interestingly, compared to their mono use, the ternary incorporation of RCB, RWT and RCW was confirmed to highly increase the sustainability of geopolymer binders.