Spatial Variation of Physical, Mechanical, and Thermophysical Properties of 3D Printed Concrete Across a Full-Scale Wall (2024-05)¶

3D-printed concrete (3DPC) is a layered anisotropic material whose properties are significantly impacted by the production parameters. To design and analyze large-scale printed structures, it is vital to understand the spatial variation of material properties throughout full-scale printed components. Presented study addresses this need by presenting a comprehensive experimental investigation that explores the variation of physical, mechanical, and thermophysical properties across a full-scale 3DPC wall with an approximate height of 2.36 m. The cores extracted from the wall were categorized in terms of the extraction location along the wall height (upper (U) and lower (L)) and the alignment of the specimen’s longitudinal axis with respect to the printing space (printing (P), translation (T), and deposition (D) direction). Additionally, direct shear and four-point bending tests were carried out on printed beams. Control samples, mold-cast from the same concrete mix, were used for comparison. Obtained results indicated a pronounced anisotropy and property variation along the 3DPC wall height. These were linked not only to the frequency and orientation but also to the porosity of the interfaces which was significantly influenced by the self-weight compaction of the layers and the progressively increasing concrete viscosity caused by pump system heating over time. CT investigations, rate of water absorption, and water penetration tests revealed sparse and less connected interstrip and interlayer porosity in the L samples. Depending on the sample orientation and loading direction, compressive strength, elastic modulus and splitting tensile strength increased by up to 108 %, 53 %, and 100 %, respectively, in the L samples when compared to the U samples. The same trend was observed in the Poisson’s ratio, albeit to a lesser extent. The triaxial thermal conductivities of the L samples calculated from the transient plane source measurements were up to 26 % higher than those for the U samples. Given the limited number of studies on real-scale applications, the presented research can serve as a benchmark, offering valuable insights to explore and validate the 3DPC behavior on a large scale.