Three-dimensional concrete printing (3DCP) offers an accurate, formwork-free, and resource-efficient construction process; however, the absence of vibration and compaction often results in increased porosity and reduced durability. This study investigates the influence of nano-calcium carbonate (NC), acting as a nano pore-filler, on the durability and other physical properties of 3DCP. NC was incorporated at dosages of 0–3% by weight of cement, and specimens were fabricated using a laboratory-scale 3D printing machine. Durability performance was evaluated after 120 days under plastic-wrapped curing, sulfuric acid exposure, and magnesium sulfate immersion. In addition, thermal conductivity and sound absorption were measured to identify the effect of pore structure modification by NC. The results show that NC enhances matrix densification and mechanical performance up to an optimal dosage of approximately 2%, beyond which its effectiveness decreases. Under magnesium sulfate immersion, the strength decreased slightly but improved with increasing NC content up to about 2%. In the case of sulfuric acid exposure, the strength decreased significantly after 120 days; however, it still increased with increasing NC content. Incorporating NC into 3DCP appears to provide improved resistance to both magnesium sulfate and sulfuric acid exposure. Thermal conductivity increased with NC addition, indicating improved solid-phase continuity, whereas sound absorption decreased due to the reduction in porosity. These findings demonstrate that nano-calcium carbonate can effectively refine pore structure and improve durability-related performance, contributing to extended service life and more sustainable 3D-printed cementitious materials in the built environment.
Chumpol et al. (Wed,) studied this question.