Application of a harmonized life cycle assessment method for supplementary cementitious materials in structural concrete

Abstract

Substitution of Ordinary Portland Cement (OPC) with supplementary cementitious materials (SCMs), such as fly ash and slag, can reduce energy consumption, thus a consequent depletion in carbon footprint. While there are some methods available for assessing sustainability, most studies considered only one or two aspects. Due to a lack of integration and uncertainty analysis, it is difficult for decision-makers to integrate possible mechanical, environmental, economic, and social measures for concrete selection. Therefore, this study performs regression analysis and Monte Carlo simulations on mechanical properties of concrete with different mix proportions of SCMs. The probabilistic distribution of uncertainty analysis shows concrete strength has a higher association with cement mix (r > 0.8) than slag (r = 0.77) and fly ash (r = 0.63) mixes. Harmonized method of life cycle impact assessment (LCIA) has been presented to categorize impacts from short-term to long-term perspectives in terms of human health damage (DALY), ecosystem damage (species.year), and resource availability ($) to take care of both environmental and social aspects. Single objective Pareto analysis determines cement's optimum replacement can happen with 20% fly ash and 30% slag. A total reduction of 2745 megatons CO2 and monetary savings of 209 billion dollars is feasible by replacing 50% of the produced cement globally (4.1 gigatons) with SCMs, which can be rewarded for human health and ecological recoveries.