Effect of salt on thermal properties of natural stone curtain wall materials: A case study of red sandstone

Abstract

Understanding and optimizing the hygrothermal performance of building enclosures in coastal areas require knowledge of the hygrothermal performance parameters of salt-containing porous building materials. In coastal regions, the presence of salt influences the thermophysical properties of porous materials, leading to alterations in the heat transfer capabilities and surface optical characteristics, which can diminish a building's energy efficiency. Current research on the thermophysical properties of porous materials under saline conditions is limited. This study compared and analyzed the thermophysical properties of red sandstone with different salt contents. The study employed a guarded hot plate apparatus, hot disk, differential scanning calorimetry, spectrophotometer, and hemisphere emissivity meter to test both the dry and moist specimens. Thermal conductivity, specific heat capacity, solar spectral reflectance, and hemispherical emissivity measurements were successfully obtained. The findings indicate a significant impact of salt on the thermophysical properties of moist specimens, whereas the effect on dry specimens was negligible. Furthermore, utilizing micro-CT scanning and equilibrium sorption tests, this research elucidates the influence mechanism of salt on the thermal properties of porous materials, attributing it primarily to alterations in porosity and moisture content. The research results can provide reference for the thermal performance analysis and energy consumption optimization of the enclosure structure in the salt-containing hot and humid climate region.