Experimental study on the effect of salt on the water absorption characteristic of cement mortar

Coastal buildings are exposed to salt spray environments for prolonged periods of time, and salt accumulates in the building walls. The effect of salt on the water absorption characteristics of the material is unclear and requires further investigation of the coupled heat and moisture transfer processes in coastal building walls. To address this issue and quantify this effect, cement mortar specimens were pretreated, and a capillary water absorption experiment was conducted on a saltcontaining cement mortar to obtain the laws of the water absorption coefficient and capillary saturation moisture content with salt content. In addition, equations for fitting the water absorption coefficient and capillary saturation moisture content of salt-containing materials were established by integrating the salt impact factors proposed in this study. The obtained results showed that as the salt content increased, the water absorption coefficient first increased and then decreased, with a peak increase of 7.5% compared to that of the control group. The capillary saturation moisture content gradually decreased with increasing salt content, decreasing by 15.8% at the maximum salt content. Combined with scanning electron microscopy (SEM) observations of microstructural changes in specimens containing different amounts of salt, it was inferred that the dominant factors affecting the water absorption characteristics would be different when the salt content of the material was varied. In addition, the optimal formulae for the water absorption coefficient and capillary saturation moisture content of salt-containing materials were obtained.