Study on Anisotropic Thermal and Mechanical Properties of 3D-Printed Scrap-Aerogel-Incorporated Concrete (SAIC)

This study investigates the feasibility of using scrap aerogel (SAG) generated during silica aerogel production as a partial substitute for sand in 3D concrete printing. Through comprehensive experiments and finite element analysis, the printability, thermal insulation properties, and mechanical characteristics (compressive strength and flexural strength) of 3D-printed scrap-aerogel-incorporated concrete (3DP-SAIC) were evaluated at different SAG replacement ratios. The results indicate that the thermal conductivity of the concrete decreases with increasing SAG content. When 30% of the sand is replaced by aerogel, the thermal conductivity perpendicular to the printed layer direction is reduced by 40.90%. The thermal properties of SAIC closely resemble those of aerogel concrete (AIC) while significantly reducing manufacturing costs. Compared to existing 3D-printed aerogel concrete, this study achieves a 73.1% cost reduction. Compared to standard cast specimens (SC-SAIC), 3DP-SAIC exhibits pronounced anisotropic thermal behavior. The study also evaluated the reinforcement effects of four basalt fibers (BF) with different aspect ratios on the mechanical properties of 3DP-SAIC. Although BF provides limited enhancement to compressive strength, it significantly boosts flexural strength. Specifically, BF with a length of 12 mm and a diameter of 17 μm increases flexural strength by 26.97%. These findings highlight the application potential of recycled aerogel in 3D-printed concrete, offering a sustainable thermal insulation solution with suitable mechanical properties for green building technologies.