Thermal and Mechanical Properties of 3D-Printed Fiber-Reinforced Lightweight Concrete Based on Air Entrainment and Hollow Glass Microspheres (2025-10)¶

This study aims to enhance the thermal insulation properties of 3D printed concrete by introducing air-introducing agents and hollow glass microspheres (HGM). Experimental evaluations were conducted to evaluate the effects of HGM replacement rate, water-to-binder ratio (w/b), basalt fibers, air entrainment, and thickeners on the workability, printability, thermal properties, and mechanical performance of 3D printed hollow glass microsphere air-entrained concrete (3DP-HGMAEC). The results indicate that low HGM replacement rates and high w/b increase air entrainment, which in turn reduces printability and mechanical strength. Basalt fibers can mitigate some of the negative effects of air entrainment; however, they also lead to an increase in the anisotropy of both flexural strength and splitting tensile strength. Thickeners had minimal influence on mechanical properties but enhanced printability. The developed 3DP-HGMAEC achieved a reduction in thermal conductivity of up to 71% compared with normal concrete, while maintaining a compressive strength of at least 35 MPa. In addition, a multiphase concrete thermal conductivity calculation model that accounts for interfacial thermal resistance has been developed to provide guidance for the design of 3DP-HGMAEC. This work offers a new material preparation method and a theoretical model for the production of 3D-printed concrete structures integrating energy-saving and load-bearing functions, such as thermal insulation load-bearing walls and columns.