Development of environmentally sustainable geopolymer-based soil solidifiers using waste siding and glass powders

This study develops an environmentally sustainable soil solidifier by utilizing Siding Cut Powder (SCP), an industrial by-product, activated with Earth Silica (ES), an innovative alkaline stimulant derived from recycled waste glass. Laboratory tests were conducted on various formulations of SCP and ES, with and without additives such as Ordinary Portland Cement (OPC) and calcium hydroxide (Ca(OH) 2 ). The results demonstrated that SCP activated with ES significantly enhanced the compressive strength of the soil, exceeding the 160 kN/m 2 threshold required for construction-grade soil. The addition of OPC and Ca(OH) 2 further improved performance, while thermal treatment of SCP at 110 °C and 200 °C reduced the required amount of solidifier without compromising strength. Environmental assessments initially identified concerns regarding arsenic (As) leaching in SCP formulations, partially attributed to the recycled glass content in ES. However, the incorporation of Ca(OH) 2 effectively mitigated As leaching by forming stable calcium arsenate compounds, ensuring compliance with environmental standards. SEM-EDS analysis revealed the formation of silicate and aluminosilicate compounds, with calcium silicate hydrate (C-S-H) contributing to improved mechanical stability and durability. These findings indicate that SCP and ES provide a viable, low-carbon alternative to OPC-based solidifiers, supporting sustainable construction practices. The implications of this study include potential reductions in construction waste and carbon emissions, as well as new opportunities for recycling industrial by-products in geotechnical applications.