Life cycle assessment of a concrete 3D printing process

Purpose: 3D printing has been put forward for its supposed environmental benefit, yet to be confirmed. This article describes an environmental assessment of a 3D printing process that represents one of the most commonly used technologies in the field. It then suggests a generic framework to evaluate the environmental impact of 3D concrete printing through a parametric model. Material and methods: The studied system is a 3D printing cell based on a 6-axis robotic arm assessed through a cradle-to-cradle life cycle assessment. It provides data details for subparts of the 3D printing process allowing other researchers to compose and recombine those subparts to represent other 3D concrete printing processes and faster the inventory and eco-design process of such technologies. As the concrete sector usually focuses on its global warming contribution, an analysis of relative importance of environmental categories was performed using both normalization/weighting and an endpoint evaluation. An uncertainty assessment based on the pedigree matrix allows to evaluate result confidence. Results and discussion: The results show that the main contributors to the 3D printed building element are first the high requirement concrete and second the robotic system, mainly the electronic parts. A detailed uncertainty study has been conducted to evaluate error margins. The sensitivity study on the electricity mix also shows the relative low importance of the technology localization to assess its environmental balance. Conclusions: A first sketch of a generic framework to assess extrusion-based 3D printing in the construction sector is proposed. A detailed LCA is performed and highlights ways of improvement of the technology. Further research on similar technology and scale-up scenario is needed to consolidate the framework and is seen as main research perspectives of this work.