Comparative life cycle assessment (LCA) of geopolymer cement manufacturing with Portland cement in Indian context

Abstract

India is the second-leading cement producer in the world after China. Cement causes huge carbon footprint during the production and transportation of materials. Various efforts are being made to reduce the environmental impacts. Among the notable developments are the use of by-product or secondary material to develop new binders such as geopolymer cement. This paper contains a cradle-to-gate life cycle impact assessment of two types of geopolymer cement produced from blending fly ash and slag, and blending fly ash and cement in an Indian scenario. As there is no standard data available for geopolymer cement production, the primary data used were collected by producing geopolymer cement at pilot scale (5 t/d). In an Indian context, the geopolymer cement significantly reduces the global warming potential (267 kg CO2-Equiv.), abiotic depletion potential fossil (3092 MJ), abiotic depletion potential element (1.18 e−3 kg Sb-Equiv.), human toxicity potential (249 kg DCB-Equiv.), and terrestrial ecotoxicity potential (0.438 kg DCB-Equiv.) with blending fly ash and slag. The geopolymer cement produced from fly ash and slag reduces the global warming potential by 70%, abiotic depletion potential fossil by 49%, abiotic depletion potential element by 34%, and terrestrial ecotoxicity potential by 77% when compared with ordinary Portland cement of the building and construction industries. In case of geopolymer cement, the maximum impact on the environment is due to the use of an alkali solution. Based on the analysis, geopolymer cement appears more sustainable than traditional cement and thus has good potential as an alternate binder.