LIFE CYCLE ASSESSMENT AND MULTI- CRITERIA DECISION ANALYSIS APPROACH FOR CARBON EMISSION EVALUATION IN 3D PRINTED GEOPOLYMER CONCRETE

ABSTRACT The construction industry accounts for a large share of worldwide carbon emissions due to the widespread use of Ordinary Portland Cement (OPC) and resource-intensive construction practices. As environmental issues become increasingly important, 3D-Printed Geopolymer Concrete (3DPGC), which uses industrial by-products like fly ash and ground granulated blast furnace slag in combination with decreased reliance on OPC, is gaining traction as a sustainable material alternative. This review paper summarizes the latest advancements in the integration of Life Cycle Assessment (LCA) and Multi-Criteria Decision Analysis (MCDA) as tools to assess the environmental sustainability and overall performance of 3DPGC. According to the literature analyzed, geopolymer concrete provides substantial reduction in greenhouse gas emissions, embodied energy, and natural resources use compared to conventional concrete. However, the environmental benefits depend on a range of factors such as alkali activator production, curing process, source of electricity, transportation, and raw materials composition. The review further points out to an increase in application of MCDA methodologies such as AHP, TOPSIS, and Fuzzy TOPSIS in order to include different criteria into sustainable material selection. The existing body of research also identifies some research gaps in relation to lack of consideration of such parameters as durability, service life, circular