Optimisation and environmental impact analysis of green dry mix mortar paving block incorporating high volume recycled waste glass and ground granulated blast furnace slag

Abstract

This research incorporates sustainable materials such as ground granulated blast furnace slag (GGBS) and recycled waste glass (RWG) as cement and fine aggregate replacement respectively to produce green dry mix mortar paving blocks. The GGBS and RWG contents in the mortar paving block were optimised using the response surface methodology (RSM), considering the performances of the ultrasonic pulse velocity (UPV), flexural and compressive strengths, water absorption, and Cantabro loss. Life cycle assessment (LCA) was also conducted to evaluate the environmental impact of the optimised green mortar paving blocks. The RSM suggested that the paving block with optimum GGBS and RWG contents of 26.5% and 91.3%, respectively, could exhibit compressive strength of 36.5MPa, which complied with the requirement for concrete segmental paving units (MA20). Excluding the mixes not fulfilling the MA20 requirement, the mix with 40% GGBS and 100% RWG exhibited the lowest values for the acidification potential (AP), global warming potential (GWP), photochemical oxidation (POCP), abiotic depletion potential for fossil fuel (ADPF), and water scarcity/strength ratio. Whereas, for eutrophication potential (EP) and abiotic depletion for elements (ADP (elements))/strength ratio, the mix with 100% RWG exhibited the lowest value. The optimised mix from RSM showed a similar performance as the two mixes.