Investigating efflorescence in salt-cement composites: The impact of surface inclination and salt waste types on resource-efficient construction materials

Disposing of excess salt from seawater desalination and the potash industry presents substantial ecological risks worldwide. This underscores the pressing need to explore reuse possibilities to mitigate environmental damage. One potential solution involves incorporating salt waste into building construction, especially in environments with low air humidity. However, this integration affects composite materials' mechanical and hydrothermal properties and results in efflorescence on the material surface. This study investigates how different surface inclinations and two types of salt waste affect efflorescence in salt cement mixtures. The primary goal of this research is to design more resource-efficient building materials by reducing cement usage while improving understanding of optimized surface design in indoor construction applications. Experimental in-situ measurements employing Confocal Laser Scanning Microscopy (CLSM) and Macro X-ray fluorescence scanning (MA-XRF) were conducted to examine salt crystallization accumulation on the salt cement surface. Our findings indicate higher efflorescence on concrete-salt surfaces with steeper inclinations (30–60 %). Furthermore, salt waste from the potash industry exhibits greater efflorescence than desalination salts, attributed to its higher sodium chloride content. This research contributes to a deeper understanding of the interactions among salt waste, cement, and surface characteristics, providing valuable insights for future advancements in construction materials science.