Building Science Performance of 3D-Printed Concrete Walls: A Review of Thermal and Hygrothermal Properties

The use of 3D-printed concrete (3DPC) for home building has been of interest to several newly formed 3D printing companies over the past few years. This interest is largely due to its time and material efficiency, as well as its flexibility in architectural design. Although the structural capabilities of 3DPC are still being researched, the enclosure aspects of printed buildings are not equally studied. Current applications of 3DPC for home building are more suitable for mild climates where there is limited risk from harsh weather and drastic temperature differences throughout the seasons. There is a void in understanding how 3DPC walls in cold climates will perform with respect to heat transfer through the wall, which can affect the energy consumption of the building. Therefore, this literature review will explore select numerical and experimental research studies that have been completed on the building science aspects of 3DPC walls and identify gaps for future research. While the main aspect of interest in building science for this study is related to the thermal conductivity property of 3DPC, other aspects are also addressed to a lesser degree. The review then focuses on the thermal performance of the printed concrete, the print configuration and the cavity infill, various waterproofing methods, and hygrothermal properties relating to humidity levels, freeze–thaw cycles, corrosion and mold risk. The research methodology for this review consisted of using keywords to search for relevant 3DPC documents with some reference to building science aspects, categorizing the literature contents based on relevance, recency and quantifiable data, providing a summary of the studies performed and their conclusions, and suggesting any remaining knowledge gaps that merit future studies. Based on the literature review, it is very unlikely that only adjusting the concrete mixture, changing the print configuration or infilling the cavities of 3DPC walls with insulation will satisfy thermal performance requirements across climate zones. The literature review identifies a few future research and study directions. To meet energy standards such as the International Energy Conservation Code (IECC) and avoid thermal bridging, studies need to explore how a continuous layer of insulation can be incorporated into the wall assembly, whether it is interior or exterior, and how it would affect energy consumption. The humidity distribution and risk of condensation across assemblies should also be further researched to determine if they impact the placement of continuous insulation, as well as the risk of corrosion for any structural metal elements in the assembly. Regarding ongoing 3DPC construction, this study shows that while there exists a good understanding of the material and print characteristics, there is a need to use sensors and monitoring systems within current 3DPC builds to gather data on the enclosure performance through different seasons for future improvement.