Life cycle assessment of limestone calcined clay concrete: Potential for low-carbon 3D printing

Limestone calcined clay cement is being promoted throughout the construction industry as a way to considerably reduce the cement proportion in concrete mixtures. At the same time, concrete 3D printing could save resources by placing concrete material only where its functionalities are maximized. This study addresses the need for a quantification of the environmental impacts related to the material acquisition phase regarding a low-clinker 3D printing material. Compared to a 30 MPa 3D printing material from the literature, a 3D printable LC3-based concrete with low clinker content in the Quebec context displays a 36 % climate change score reduction with the same compressive strength (46 % reduction in the French context). A small impact shift is noticed in 6 out of 16 midpoint indicators (5 in the French case), mainly due to the calcined clay production. However, it is offset by the significant reduction in other indicators when considering an endpoint assessment. When considering different sourcing scenarios, a global warming potential variability of up to 15 % is observed. LC3 remains a viable solution for the mitigation of greenhouse gas emissions in the context of concrete 3D printing as it provides mechanical strength and enhanced structuration rate for low-clinker materials. However, a specific attention should be accorded to the calcined clay plant locations, especially when the calcined clay content is higher than the value used in this study. As a perspective, a mix design tool could allow the optimization of environmental impacts depending on expected fresh and hardened properties. • A printable blend is assessed in the Quebec and French contexts. • LC3 allows a 36 % to 46 % reduction in GWP for concrete 3D printing. • For other indicators, improvements prevail over degradations at the endpoint level. • Calcined clay sourcing induces an LC3 GWP variability of 15 % in the Quebec context.