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

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 36.5 MPa, 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.

Influence of Liquid-to-Solid and Alkaline Activator (Sodium Silicate to Sodium Hydroxide) Ratios on Fresh and Hardened Properties of Alkali-Activated Palm Oil Fuel Ash Geopolymer.

Malaysia is one of the largest palm oil producers in the world and its palm oil industry is predicted to generate a large amount of waste, which increases the need to modify it for sustainable reuse. The green geopolymers produced from industrial waste can be a potential substitute for cementitious binders. This type of polymer helps reduce dependency on cement, a material that causes environmental problems due to its high carbon emissions. Palm oil fuel ash (POFA) geopolymer has been widely investigated for its use as a sustainable construction material. However, there is still uncertainty regarding the total replacement of cement with POFA geopolymer as a binder. In this study, we examined the effects of different material design parameters on the performance of a POFA-based geopolymer as a building material product through iterations of mixture optimisation. The material assessed was a single raw precursor material (POFA) activated by an alkaline activator (a combination of sodium hydroxide and sodium silicate with constant concentration) and homogenised. We conducted a physical property test, compressive strength test, and chemical composition and microstructural analyses to evaluate the performance of the alkali-activated POFA geopolymer at 7 and 28 days. According to the results, the optimum parameters for the production of alkali-activated POFA paste binder are 0.6 liquid-to-solid ratio and 2.5 alkaline activator ratio. Our results show that the use of alkali-activated POFA geopolymer is technically feasible, offering a sustainable and environmentally friendly alternative for POFA disposal.