Evaluating the Environmental Performance of Blended Cement-Based Concrete: A Comparative Life-Cycle Analysis to Derive an Environmental Score

Abstract

The production of portland cement, particularly clinker, is a major source of CO2 emissions in concrete manufacture. Blended cement has emerged as a low-carbon alternative to improve sustainability, but the lack of comparative environmental assessment methodologies and a practical material selection process hampers the adoption for industrial applications. This study reports a comparative life-cycle assessment of blended cement and blended cement concrete to derive an environmental score for industry-applied mix designs. SimaPro life-cycle assessment (LCA) software is used to analyze 18 impact categories under three exposure scenarios for industry-used standard cement types, namely, CEM II/A-S, CEM II/A-V, CEM IV/A, CEM II/B-M, CEM II/A-L, and CEM I. The findings highlight the potential of blended cement to mitigate the negative environmental impacts associated with conventional cement production. Blended cements exhibit lower values in major impact categories including global warming potential, acidification potential, and eutrophication potential compared to CEM I. This is primarily due to the incorporation of supplementary cementitious materials that reduce clinker content. However, certain compositions of blended cement concrete, such as CEM II/A-S, display increased impact in some categories, indicating the influence of variations in the availability and processing requirements of cementitious materials. The study emphasizes the importance of considering the entire life cycle of materials, including specific exposure conditions during the use phase. Concrete mixes with higher strength tend to have greater environmental impacts, while blended cement types generally exhibit lower impacts across various categories. Based on the environmental score evaluation, CEM II/B-M, CEM IV/A, and CEM II/A-S have lower impacts compared to CEM I. The derived environmental score methodology can aid material selection, promoting sustainable practices in the construction industry.