Impact of dissolved salt type and content on mechanical and physical properties of porous cementitious materials

Salt precipitation is a major factor influencing the internal characteristics of concrete during curing. In this study, the impacts of the type and concentration of various salts on the characteristics of porous cementitious materials were investigated using a series of engineered porous concrete specimens. The results indicated that chemical interactions among interparticle cement, clay mineral, calcite, and different salts in aqueous media during 28 days of curing could alter properties such as porosity, permeability, and mechanical strength depending on salt concentration. Among these, concrete permeability was most affected. There was an inverse relationship between the content of monovalent ions and concrete porosity and permeability. In contrast, for divalent ions in the concentration range of 10–30 g/L, an optimum value of 15 g/L resulted in the lowest salt precipitation and highest porosity and permeability values. Furthermore, different salts present during curing led to an increase of up to 16% in compressional wave velocity. Based on the results of ultrasonic and uniaxial compressive strength (UCS) tests, linear and exponential correlations were observed between porosity and compressional/shear wave velocities, while UCS was exponentially related to porosity.