Influence of salts and moisture on the thermal properties of porous building materials

Accurate thermal parameters of building materials are indispensable in assessing the energy performance and durability of buildings by hygrothermal modeling. The presence of moisture and salt alters the heat and moisture behaviors of the building materials. However, knowledge of their joint influence on the thermal properties of building materials is still limited. This study experimentally investigates the variation in the thermal properties of two types of sintered bricks in the presence of single salts and salt mixtures across the full moisture content range from saturation to dryness. The results confirm that the thermal properties increase with moisture content. The effect of salts on thermal properties is inconsistent in different moisture states. In the dry state, the thermal conductivity and thermal diffusivity of saline bricks increase with increasing salt concentration, while the specific heat capacity decreases. At a moist state, compared to salt-free bricks, the thermal conductivity and specific heat capacity of salted bricks decrease with increasing molarity of salt solutions. Sodium sulfate has a more pronounced influence on the thermal properties than sodium chloride. Finally, the fitting models are proposed to describe the relationships between thermal properties and the moisture and salt content of the bricks. This research is expected to extend the existing dataset and provide precise data for modeling and predicting the energy performance and salt deterioration of the building envelope subjected to salt invasion.