A construction 3D printing system could result in automated infrastructure development at reduced cost and time, significantly boosting overall productivity. Although there has been a growing interest in using construction 3D printing for projects such as house construction, implementing this innovative technology for infrastructure development, particularly bridge construction, has not been investigated as extensively. This study aims to compare the environmental impact of precast and 3D concrete printing (3DCP) techniques with a pedestrian bridge case study, located in Louisiana, where the bridge elements were 3D printed off-site and then transported and assembled on the bridge site. A detailed cradle-to-site life cycle assessment has been performed from the standpoint of material, construction, and installation stages, using an open-source software called OpenLCA. The results of this study showed that the mixtures commonly used in 3DCP have a higher negative environmental impact compared to the precast method due to the higher percentage of cement used in these materials. However, since 3DCP used less material than the precast technique, there is no significant difference in the environmental impact of the total concrete used between the 3DCP and precast bridges. In addition, due to the use of reinforcement and formwork in the precast technique, the environmental impact of the total materials used in the precast bridge was more adverse than the 3DCP bridge. Notably, due to use of electricity for printing, the negative environmental impact of the construction process in 3DCP was significantly higher than in the precast technique. Finally, the total carbon dioxide equivalent emitted during the construction of the 3DCP bridge was 80% of the precast bridge.

Tran-SET Project: 21STLSU04