A comparative study on environmental performance of 3D printing and conventional casting of concrete products with industrial wastes

3D printing construction techniques are believed to have potential sustainability benefits, including improved resource efficiency, increased construction productivity, and construction of complex geometries without supporting structures. 3D printable concrete materials, when introducing industrial wastes such as fly ash, silica fume, and slag, may also bring additional sustainability benefits. These advantages need to be verified quantitatively. This study investigated the environmental impact of 3D printable concrete materials using industrial wastes compared with the conventional ones via life cycle assessment (LCA). Two types of concrete materials applied in concrete casting or 3D printing were compared, that is, cement-based concrete and geopolymer concrete. The results indicate that using waste materials as cement replacement could bring environmental benefits; however, such environmental benefits might be diminished with increasing activator content in geopolymer concrete for 3D concrete printing. Based on the material-level LCA results, this study further conducted an LCA study at the component level, which investigated the life-cycle environmental impact of concrete components of different shapes constructed by Contour Crafting method. Results show that the potential environmental benefit of 3D concrete printing increases with the level of building complexity while decreases with the reuse times of formwork, which leads to the conclusion that 3D concrete printing method is more desirable for constructing non-repetitive freeform concrete structures.