Pore structure is an important factor that affects both vapor adsorption and water absorption performances of the expanded perlite insulation mortar. This study aims to explore the change in the pore structure of the expanded perlite insulation mortar in heat-rain cycles and investigate the effects on capillary water absorption and vapor adsorption performances. The expanded perlite insulation mortar specimens was subjected to 160 heat-rain cyclic test, and the distribution characteristics of the pore structures of the specimens after different heat–rain cycles in vacuum saturated water absorption, capillary water absorption, and vapor adsorption processes were measured via nuclear magnetic resonance. According to the test results, the pores with a size of greater than 1 μm in the expanded perlite insulation mortar determined the variation in total pores. The pore size can be classified into different ranges according to the performance in capillary water absorption and vapor adsorption. The calculated results of the fractional dimension suggest that the structure variation rules of different types of pores can be characterized by the fractional dimension. The relationship between the macro-performance parameters and the micro-structure can be established by using the fractional dimension as the linkage to provide reference for the hydrothermal evaluation of the whole expanded perlite external thermal insulation composite system.

孔结构是影响膨胀珍珠岩隔热砂浆的蒸气吸附和吸水性能的重要因素。本研究旨在探讨膨胀-珍珠岩保温砂浆在热雨循环中孔隙结构的变化，并研究其对毛细吸水率和蒸气吸附性能的影响。膨胀珍珠岩保温砂浆试样进行160热雨循环试验，测定在真空饱和吸水率，毛细水吸收，和蒸气吸附过程不同热雨次循环后的样品的孔结构的分布特性通过核磁共振。根据测试结果，膨胀珍珠岩隔热砂浆中大于1μm的孔决定了总孔的变化。根据毛细管吸水和蒸气吸附的性能，孔径可以分为不同范围。分数维的计算结果表明，不同类型孔隙的结构变化规律可以用分数维来表征。宏观性能参数与微观结构之间的关系可以通过使用分数维作为联系来建立，为整个膨胀珍珠岩外保温复合体系的水热评价提供参考。