Sustainable construction processes through additive manufacturing: Screening strategies to reduce environmental impacts of 3D concrete printing

Additive manufacturing (AM) consists of processes that involve joining materials to make parts from 3D models, normally layer by layer. The AM approach has been largely used in industrial applications, but in the construction sector, it is still an emerging technology. In the construction sector, 3D concrete printing (3DCP) represents a driving force of AM implementation. On the one hand, AM, and more specifically 3DCP, has a high potential to enhance the sustainability of construction processes by enabling optimized material distribution, eliminating formwork, and reducing waste generation. On the other hand, 3DCP also presents some environmental issues, mainly related to the high binder intensity required for extrudability. This study consisted of a prospective analysis of screening strategies to reduce the environmental impacts of 3DCP on construction sites. Different strategies were considered for the materials used and the printing processes. Environmental impact categories from Life Cycle Assessment (LCA) were used together with complementary indicators involving energy demand and materials circularity. The LCA was conducted in four phases: goal and scope definition, Life Cycle Inventory (LCI), Life Cycle Impact Assessment (LCIA), and Interpretation. The Scenario results were assembled in a 3DCP construction workflow that shows the hotspots of environmental burdens for each strategy for different categories. The results indicate that material choices play the most important role in reducing environmental impacts, particularly climate change-related emissions. However, differences in 3DCP processes themselves also showed interesting variations across impact categories other than climate change. So, this study provided an insightful LCA-based quantitative analysis of strategies to reduce the environmental impacts of 3DCP, and the main finding is that, despite the predominant relevance of material selection, 3DCP construction strategies can also play an important role in further enhancing sustainability and should not be overlooked.