Comparative environmental assessment of limestone calcined clay cements and typical blended cements

Abstract

Decarbonization of the cement and concrete industries is one of the top priorities on the path to a carbon-neutral economy. This article presents a novel model for evaluating the emissions from the production of metakaolin (MK) as a supplementary cementitious material used in ternary blended cements (e.g., 35% metakaolin, 15% limestone, and 50% portland cement) and an accompanying decisions-support tool (MKC-Tool). Applications with a case study in California showed 36%-39% reductions in greenhouse gas (GHG) emissions from ternary blends with MK compared to portland cement. Compared to commercially available blended cements, the ternary blend showed the lowest global warming potential. All the cements containing fly ash showed higher GHG intensities than the ternary blend (16%-42% higher GHG emissions). The development of cements made with portland cement, metakaolin, and limestone at an industrial scale will have the potential to contribute 5%-50% to the global reduction of GHG emissions from the cement industry.