Electrical Resistivity and Elevated Temperature Performance of 3D Printed Concrete Containing Nanosized Radiation Shielding Admixtures (2025-12)¶

This study aims to evaluate the impact of incorporating radiation-shielding particles on the electrical resistivity and thermal performance of 3D-printed concrete (3DPC). Three types of 3DPC were evaluated: a plain (control) 3DPC and two modified mixes containing heavy-weight radiation-shielding nanoparticles. The first mix contained a mixture of pristine Bi2O3/Gd2O3 particles in a 1:1 mass ratio, while the second type used silica-coated Bi2O3/Gd2O3 particles in the same ratio. In both modified mixes, 2.5 vol% of cement was replaced with nanoparticles. The experimental program involved measuring electrical resistivity and assessing thermal performance through dynamic elastic modulus and compressive strength after exposure to elevated temperatures of 450 °C and 600 °C. Electrical resistivity measurements revealed that pristine particles significantly reduced electrical resistivity of 3DPC, while the mix containing silica-coated particles mitigated this effect. These results align with previous findings on nanosilica-induced microstructural densification. Thermal performance was assessed through compressive strength and dynamic elastic modulus after exposure to 450 °C and 600 °C. Printed specimens showed slightly higher strength losses than the cast ones, attributed to their layered structure and interlayer debonding. However, overall differences between cast and printed specimens, as well as between control and nano-modified mixes, were minimal. The results suggest that the inclusion of 2.5 vol% radiation-shielding admixtures has a limited impact on the elevated-temperature resistance of 3DPC, however further studies on interlayer adhesion are recommended.