Life Cycle Assessment of the Geopolymer Concrete Containing Fly Ash, Metakaolin and Zeolite

Abstract

The construction industry is a major contributor to global carbon emissions, primarily due to the widespread use of ordinary Portland cement (OPC) in concrete production. To address this environmental challenge, this study evaluates the sustainability of geopolymer concrete (an alternative binding material synthesized from industrial by-products (fly ash and metakaolin) and natural materials (zeolite)) using Life Cycle Assessment (LCA). The environmental impacts of geopolymer concrete were compared to those of conventional OPC-based concrete across key impact categories, including global warming potential, resource depletion, and toxicity.
The LCA was conducted following the ISO 14040 and 14044 standards, with a cradle-to-gate system boundary and a functional unit of 1 cubic meter of concrete. The results demonstrate that geopolymer concrete, particularly the MK20 formulation, significantly outperforms conventional concrete in terms of environmental sustainability. For instance, the global warming potential of geopolymer concrete was up to 99% lower than that of conventional concrete, primarily due to the avoidance of energy-intensive OPC production. Additionally, geopolymer concrete showed substantial reductions in human toxicity, aquatic and terrestrial ecotoxicity, and abiotic resource depletion. Normalization of the results using the CML-baseline method further confirmed the superior environmental performance of geopolymer concrete across all impact categories. However, the study also identified the need to address the environmental impacts of alkali activators, which contribute to the overall footprint of geopolymer production.
The findings highlight the potential of geopolymer concrete as a sustainable alternative to conventional concrete, offering significant environmental benefits while maintaining comparable mechanical properties. This research supports the transition toward greener construction practices and contributes to global efforts to mitigate climate change. Future studies should focus on optimizing mix designs, exploring alternative activators, and assessing the long-term durability of geopolymer concrete to further enhance its sustainability and promote its widespread adoption in the construction industry.