Performance Evolution and Balance in the Curing Mechanism of Inorganic Thermal Insulation Mortar: A Review

Inorganic thermal-insulation mortars can effectively reduce the energy consumption and carbon emissions of both existing and new buildings while maintaining the thermal stability of building envelopes. Compared with conventional mortars, these materials exhibit more pronounced multiscale coupling during curing, and their microstructural evolution and macroscopic properties are highly sensitive to environmental variables, particularly temperature, humidity, and ionic concentration. This review systematically summarizes the effects of high-temperature curing, high-humidity curing, artificially introduced ions, and special curing regimes on the mechanical properties, durability, thermal conductivity, and fire resistance of inorganic thermal-insulation mortars. The reviewed studies indicate that hydration, geopolymerization, and CO₂-curing reactions can all promote microstructural densification and thus enhance mechanical performance and durability. Elevated temperature and humidity generally accelerate reaction kinetics, intensify internal hydration, and facilitate the generation and deposition of gel products, thereby refining the pore structure and improving strength development. However, the same densification process may also increase the continuity of the solid phase and form more effective heat-transfer pathways, which is unfavorable for thermal-insulation performance. Mildly alkaline curing environments can further stimulate binder reactions and improve matrix compactness, although excessive ionic activity may negatively affect pore stability and long-term performance. Among the coupled curing conditions, wet-dry cycling appears to provide a more favorable balance between mechanical-property development and pore-structure preservation, because periodic humidity gradients can enhance strength formation, stabilize the interfacial transition zone, and reduce cracking sensitivity. Overall, the effect of curing on inorganic thermal-insulation mortars is governed by the competition and balance between reaction enhancement, pore-structure evolution, and interfacial stabilization. Future curing design should therefore focus on system-dependent optimization to achieve a rational balance among mechanical performance, thermal insulation, and fire resistance.