Assessment of the Environmental Performance of Blended Cements from a Life Cycle Perspective: A Systematic Review

Supplementary cementitious materials (SCM) are gradually depicted as the gateway to sustainability for the cement industry. In light of this, life cycle assessments (LCA)s of various blended cements have been conducted to evaluate their environmental impacts. However, these LCAs have yet to be compiled, compared and synthesized to be of use to decision makers and researchers in this field of study.By the means of a systematic review, this article aims to coherently articulate and unify LCAs of blended cements currently available in the literature in order to create a reference for stakeholders and researchers. It also aims to outline the key challenges concerning LCAs of SCM-based cements to guide future research.A total of 32 studies were analysed. From each study, key elements from every step of the LCAs were extracted then compared. The review revealed that 11 types of SCMs were studied with SCM content ranging from 3 % to 85 %. Most of the papers conducted cradle-to-gate LCAs of 1 ton of cement, focusing chiefly on the global warming potential (GWP) indicator and adopting the IPCC method. A statistical comparison of the impact assessment results suggested that limestone calcined clay cement could be the most promising solution to the cement industry, with an average GWP of 517 kgCO2eq/ton of cement and SCM content of 46%, despite the large variability of impact assessment results.However, the limited amount of assessed impact categories, the exclusion of durability and compressive strength from the functional unit and the quasi-absence of uncertainty analyses are major weaknesses of the papers, which may mislead decision-makers. Besides, the lack of available LCAs of blended cements and the wide diversity of impact assessment methods hinder consolidation efforts. These points need to be addressed in future studies so that references can be built for the benefit of stakeholders.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.