Environmental impacts of thermally activated clays for low carbon cement production

The environmental impacts of activated clay produced using a wide range of clay mineralogy (with varying carbonate content), fuels (including alternative fuels), and thermal activation technologies were assessed using the life cycle assessment methodology. Global warming potential (GWP) values for thermally activated clays produced using the four different technologies and six fuel use scenarios ranged from 186 to 360 kg CO 2 -eq. per tonne of activated clay. Depending on the fuel type, thermally activated clay can have a non-biogenic GWP of 103–360 kg CO 2 eq. per tonne, biogenic GWP of 29–94 kg CO 2 eq. per tonne. Changing the fuel type can decrease GWP by up to 30% (both biogenic and non-biogenic) and 43% (only non-biogenic), whereas changing technology can decrease GWP by up to 28%. The variability in the GWP of LC3 containing 50%, 35%, and 25% Portland clinker was assessed, where activated clay contributed 6–14%, 9–22% and 14%–30% of the GWP, respectively.