Life cycle assessment (LCA) and the influence of alkaline activator content on mechanical and microstructural properties of geopolymer mortar

Abstract

The geopolymer binder is gaining prominence as an eco-friendly alternative to ordinary Portland cement (OPC), aiming to decrease CO₂ emissions during the manufacturing of OPC. Geopolymers, which are mineral-based polymers formed from materials rich in silicates and aluminates, undergo a complex process of aluminosilicate gel creation through polymerization when activated by alkaline substances. The proportion of alkaline solutions used plays a pivotal role in the process of geopolymerization. Hence, comprehending the impact of alkaline activator content on geopolymers' behavior is imperative. To address this, a study was conducted to assess how the ratio of Na₂SiO₃ to NaOH and the concentration of NaOH affect the synthesis of geopolymer mortar. The mechanical and microstructural characteristics of the geopolymer mortar samples were thoroughly examined. The findings demonstrate that samples with a Na₂SiO₃ to NaOH ratio of 1.5 and 16 M NaOH concentration exhibited the highest compressive strength around 36 MPa at 60 °C. The emergence of the geopolymer binder as an ecologically viable alternative to OPC is becoming increasingly evident. This substitution not only addresses sustainability concerns but also contributes to the reduction of CO₂ emissions during the production of OPC. Geopolymers, compounds characterized by inorganic polymerization, are synthesized using source materials abundant in silicates and aluminates. These raw materials, upon activation with alkaline substances, undergo a sophisticated process resulting in the formation of intricate aluminosilicate gels. The LCA of GP binder has much lower values of Embodied energy (EE) and Global Warming Potential (GWP) than the OPC based mortar, with 94% and 97% reductions respectively.