Thermal Performance of Hybrid Concrete in 3D Printing: Simultaneous Use of Normal-Weight and Foam Concrete

In recent years, 3D-printed concrete (3DPC) has emerged as a technology attracting significant attention in the construction industry due to its advantages. Especially, the use of 3D-printable foam concrete (3DPFC) offers a remarkable solution for improving the performance of 3D-printed structures, with its benefits such as sustainability, lightness, and thermal insulation. Due to its low thermal conductivity, foam concrete (FC) minimizes thermal bridges, and its lightweight nature lessens the dead load on structures. In hybrid 3D printing systems, using normal-weight concrete (NWeC) for the outer filaments and foam concrete (FC) for the inner cores provides both economic and energy-efficiency benefits. This method acts as a thermal insulator and reduces the need for thermally insulated sheathing. This study addresses the thermal performance of 3DPC systems in a simple and understandable way, focusing particularly on the role of foamed concrete in reducing thermal bridges. Previous studies have mostly focused on a single material or improvements in infill geometry. However, hybrid 3D-printed systems using NWeC and FC together within the same wall have not been sufficiently investigated holistically. In hybrid systems, using NWeC in the outer layers to provide load-bearing capacity and FC in the inner regions to improve thermal insulation stands out as a promising solution offering both strength and energy efficiency. This study brings together current findings on foamed concrete materials, infill and lattice arrangements, and thermal bridge behavior, and discusses the advantages of this multi-material approach.