A novel multi-criteria comprehensive evaluation model of fly ash-based geopolymer concrete

Fly ash-based geopolymer concrete (FA-GPC), which has better early mechanical properties, durability and environmental impact, is recognized as a low-carbon concrete that has a high potential to replace ordinary Portland cement concrete. Although scholars have analyzed the mechanical properties, durability performance and environmental impact of FA-GPC independently, few studies have considered the above properties comprehensively to guide the material selection. In this study, choosing compressive strength, sulfate erosion resistance and environmental impact, including global warming potential (GWP), acidification potential (AP), primary energy depletion (PED), as evaluation indicators to be tested and analyzed with 9 different mixtures by Life Cycle Assessment (LCA) method. Based on the gray clustering analysis (GCA) method, we established a comprehensive evaluation model, then applied the commonly used Multi-criteria decision-making (MCDM) methods, namely TOPSIS and VIKOR, to observe the conclusions of the different evaluation methods. The results indicated that: (1) Experiments on compressive strength and sulfate erosion resistance and analysis of environmental impact show that FA-GPC has good sulfate erosion resistance, the alkaline activated solution is not only the most significant factor affecting the compressive strength, but also the biggest contributor to the environmental impact. (2) The evaluation models developed successfully selected the optimal mix ratio for a given function. Although the ordering of the three methods is not the same, because they have different optimization and ranking mechanisms of GCA, TOPSIS, and VIKOR, they come to the same conclusion indicating alternative A3 is optimal. The ranking of alternatives is influenced by the preferences of decision-makers, especially those at the intermediate level.