Engineering and Life Cycle Assessment (LCA) of Sustainable Zeolite-Based Geopolymer Incorporating Blast Furnace Slag

Abstract

This study aims to investigate the preparation of zeolite-based geopolymer composites incorporating blast furnace slag at various temperatures and varying amounts of blast furnace slag as potential sustainable building and construction materials. The primary objectives were to use mining waste streams for geopolymer production and assess the mechanical behavior of these hybrid geopolymers, along with performing a life cycle assessment (LCA) to compare their environmental impact with conventional concrete. It was observed that the hybrid geopolymers attained a maximum mechanical strength of 40 MPa. Remarkably, substituting just 20% of the material with blast furnace slag resulted in a 92% improvement in compressive strength. To assess environmental impacts, a cradle-to-gate LCA was performed on different geopolymer mix designs, focusing particularly on the global warming potential (GWP). The results indicated that geopolymer concrete generated a maximum of 240 kg CO2-e/m3, which was 40% lower than the emissions from ordinary cement, highlighting the environmental advantages of geopolymer materials. Further, X-ray diffraction was used to determine the mineral composition of both raw and developed composites. Solid-state nuclear magnetic resonance (NMR) was applied to study the molecular structure changes upon incorporating blast furnace slag. The initial setting time and shrinkage of the geopolymers were also investigated. Morphological characteristics were analyzed by scanning electron microscopy (SEM). Thermal analyses confirmed the stability of the geopolymers up to 800 °C. Geopolymer composites with high thermal stability can be used in construction materials that require fire resistance. This study not only enhances the understanding of geopolymer composite properties but also confirms the substantial environmental advantages of utilizing geopolymerization in sustainable construction.