The Effects of Salt Crystallization in Ceramic Bricks in Terms of Line Deformations

The long life of bricks in different conditions, especially in the presence of moisture, promotes progressive changes in ceramic material. Over time it can cause a gradual loss of the original performance of bricks. This process is related to, inter alia, the accumulation of salt originating from the external environment in ceramic texture. The crystallization of salts in the bricks and the related process of changes in volume of ceramic material can be the reason for pressure crystallization. In addition, expansive corrosion products can form in the reaction of salts and components of ceramic body. This causes the creation of stresses in the material and its cracking. Therefore, studies were undertaken, whose aim was to determine the size of line deformation changes of ceramic materials caused by the accumulation of various salts in the bricks of different textures. The periodic exposure to corrosion of ceramic materials in solutions of NaCl and MgSO4 by alternately saturating and drying were conducted.The scope of research included determined changes of linear deformations of studied bricks, caused by crystallization of salts of sulfate, chloride, or both. As a diagnostic characteristic of the changes, measurement results of elongation samples with dimensions 250x30x65 mm cut from a brick were adopted. Based on the obtained results it has been shown that crystallization of both salts in ceramic materials increases the dimensions of bricks. The greatest deformations of bricks throughout the study period were recorded in the case of chloride salts. It was further found that exposure to corrosion leads to strong deformations and destructions of bricks in the long term. This was observed particularly in the case of the brick samples subjected to a corrosive environment containing both sulfate ions and chloride. In order to determine the causes of differentiated resistance of the bricks in corrosive environments (resulting changes of dimensions), studies on the porosity, compressive strength, tensile strength, modulus of elasticity of the bricks and observations of their microstructure were performed.