Numerical modeling of salt crystallization in masonry: A critical review of developed numerical models

Salt decay is widely recognized as one of the most common mechanisms for the deterioration of building materials in monuments, sculptures, and civil structures. Understanding how salt crystallization affects the integrity of historic structures is therefore essential. Numerical tools can be used for this purpose and for estimating the damage induced by salt crystallization; however, there is still a lack of standardized procedures for accurate simulation of this degradation mechanism. In this study, we critically review existing numerical models to identify their advantages and limitations. The considered primary balance equations, variable factors, constitutive laws, assumptions, test procedures, and boundary conditions are investigated in more detail to highlight essential features. This paper describes that numerical models are generally developed based on several simplifying presumptions, such as isothermal conditions, constant boundary conditions, and the presence of only one type of salt. The impact of hydraulic interface resistances in masonry assemblies of units and joints on the numerical analysis of salt crystallization remains unclear. Despite a general understanding of the mathematical problem, several challenges persist regarding the development of constitutive laws for salt mixtures. A more accurate and reliable predictive simulation for salt decay in masonry can be developed by addressing the open issues discussed in this paper.