Towards a green climate: Production of slag–red brick waste-based geopolymer mingled with WO3 nanoparticles with bio-mechanical achievements

Abstract

According to the sustainability concept, this work developed a green geopolymeric composite (Geo) prepared by mingling 50 wt%slag+ 50 wt%brick-waste (BW) as an alternative eco-friendly and low-cost cementitious material. The main target of this study is to fnd a solution to the problem of poor characteristics of binding materials containing high proportions of BW; most previous studies recommended using only 10–20 wt%BW. The compressive-strength results showed that replacing slag with 50 wt% BW reduced the strength from 47 to 24.6 MPa at normal curing conditions for 28-days, referring to the detrimental impact of BW on mechanical performance. In an endeavour to enhance the mechanical performance of this composite, different doses from laboratory-prepared tungsten oxide nanoparticles (0.25, 0.5, 1 wt%WO3-NPs) and hydrothermal curing at various steam-pressure/periods were used. From an economic point of view, hydrothermally treated Geo-paste modified with 0.25 wt%WO3-NPs at 3 bar/4hrs was selected as an ideal composition/curing-conditions; the compressive-strength reached 54.5 MPa exceeding the standard limit of Portland cement (42.5 MPa). This clearly shows the synergistic role of using WO3-NPs and hydrothermal curing to enhance the compressive-strength, which was confirmed using different analysis techniques. XRD, TGA/DTG and SEM/mapping proved that the catalytic performance of WO3-NPs/hydrothermal-curing participates in augmenting binding hydrates, creating a cubic-stable-phase of tricalcium-aluminate-hydrate (C3AH6) and different types of zeolitic-like structure (spherical Zeolite-NaP, rods analcime and stacked-plates cancrinite). To maximize the benefits of employing WO3-NPs in the developed composites, their anti-microbial activity was studied. The measured inhibition zone around specimens containing WO3-NPs proved that these composites have a superior self-cleaning efficiency against Candida albicans, Mucor circinelloides, Salmonella typhi and Staphylococcus aureus due to the WO3-NPs’ photocatalytic activity.