Porous 3D printed concrete beams show an environmental promise: a cradle-to-grave comparative life cycle assessment

3D Concrete Printing (3DCP) is a rapidly expanding area in the field of architecture, engineering, and construction, but very limited research has quantitatively investigated its environmental impact. The existing Life Cycle Assessment (LCA) studies on 3DCP lack clearly defined functional units of comparison, especially considering load-bearing structures. This paper investigates the potential environmental benefits of 3DCP over conventional concrete construction for structural beams based on a cradle-to-grave comparative LCA. Unlike existing studies, this paper employs a recarbonation model to account for the carbon offsetting from the use-stage of 3DP concrete, which shows significant results. The assessment includes three-beam designs, each analyzed for both prefabrication and on-site construction scenarios. While currently, 3DCP has a generally higher environmental impact due to the larger quantity of cement employed in the process, the reduction of material through infill optimization for printed beams is a promising design principle to positively offset the environmental impacts in the construction sector. The paper draws recommendations for future research on material- and recarbonation-efficient 3DCP design for load-bearing structures, as well as on material development, e.g. integration of larger aggregates and low-clinker cement.