Crystallization Pressure of Sodium Sulfate Heptahydrate

Sodium sulfate is known as one of the most destructive salts leading to the deterioration of porous materials, such as monuments, sculptures, and civil engineering structures. While sodium sulfate crystals are growing in a porous material, crystallization pressure will build up. In this study we have combined a nondestructive measurement of the concentration of the pore solution within a material by using NMR with an optical measurement of the expansion of the material during crystallization. These data permit calculation of the in-pore crystallization pressure during the growth of different crystalline phases induced by cooling in three different materials: fired-clay brick, Cordova Cream limestone, and Indiana limestone.