Optimizing supplementary cementitious material replacement to minimize the environmental impacts of concrete

With growing environmental consequences from material consumption, there is increased urgency to decarbonize the production of materials we consume frequently, including concrete. It is common to use supplementary cementitious materials (SCMs) to limit the clinker content of Portland cement and reduce greenhouse gas (GHG) emissions in concrete production. However, over-utilization of SCMs can degrade material performance and increase other environmental impacts. Here we derive quantitative methods to determine the optimal SCM to Ordinary Portland Cement (OPC) ratio (s/c) for 7 different SCMs to minimize 11 environmental impact categories while maintaining compressive strength. We find that optimal replacement levels are heavily dependent on the SCM. Notably, lower s/c in many cases lowered emissions (e.g., s/c of 0.17 kg/kg for limestone leads to ∼1.6x lower GHG emissions than a s/c of 0.42 kg/kg in 30 MPa concrete). This work demonstrates a systematic means to effectively utilize limited SCM resources to mitigate environmental impacts from concrete production.