Analysis of the Coupling Laws between Thermal Insulation Performance and Mechanical Properties of a New Vitrified Microbead (VMB) Smart Insulation Mortar for Reinforcing Existing Masonry Structures

Abstract In masonry structure reinforcement projects, exterior wall reinforcement with steel mesh and insulation layer construction are typically carried out independently. Mixing insulation materials into mortar achieves both thermal insulation and controllable strength reduction. Combining the two processes can save labor and materials, reduce costs, and minimize weight. The primary objective of this manuscript is to develop a new type of smart insulation mortar using glass microspheres (VMB), which combines insulation functionality with mechanical performance requirements, enabling the integration of reinforcing mesh reinforcement and insulation layer construction into a single process. This mortar is intended to replace traditional mortar in the insulation and reinforcement retrofitting of existing masonry structures. By analyzing the influence of different VMB replacement rates (50%, 65%, 75%, 80%) and glass fiber content (1%, 2%, 3% of mortar mass) on the coupling of mechanical and thermal insulation properties of the insulation mortar. The analysis results indicate that as the volume replacement rate of new glass microspheres (VMB) increases, the density of the insulation mortar decreases, porosity increases, compressive and flexural strength decrease, but thermal insulation performance improves; as the glass fiber content increases, flexural strength improves significantly in the 0%-2% range, compressive strength fluctuates slightly, and flexural performance is optimal around 2%, with minimal impact on mortar density and porosity from small amounts of glass fiber. When the replacement rate of new vitrified microbeads (VMB) is approximately 80%, and the glass fiber content is kept around 2%, the thermal insulation and mechanical properties of the mortar can effectively meet the requirements for use. This enables the integration of exterior wall reinforcement with a steel mesh and thermal insulation layer in masonry structure reinforcement, which is of significant importance for achieving carbon peaking and carbon neutrality.