Can Portland cement be replaced by low-carbon alternative materials? A study on thermal properties and carbon emissions of innovative cements

One approach to decarbonising the cement and construction industry is to replace ordinary Portland cement (OPC) with lower carbon alternatives that have suitable properties. We show that seven innovative cementitious binders comprised of metakaolin, silica fume and nano-silica have improved thermal performance compared with OPC and we calculate the full CO₂ emissions associated with manufacture and transport of each binder for the first time. Due to their high porosity, the thermal conductivity of the novel cements is 58–90% lower than OPC, and we show that a thin layer (20 mm), up to 80% lower than standard insulating materials, is enough to bring energy emissions in domestic construction into line with 2013 Building Regulations. Carbon emissions in domestic construction can be reduced by 20–50% and these cementitious binders are able to be recycled, unlike traditional insulation materials.