Salts in Heritage Sites

There are several methods available to protect our built heritage, which represents the memory of our history and building traditions, from deterioration caused by the crystallization of salts. Some will limit the crystallization of salts in the material and thus reduce degradation without extracting the salts. Others address the problem by desalinating contaminated materials. This chapter describes the alteration of built heritage materials by salts: from the origin of the salts to the preservation of contaminated monuments. Most of the walls of heritage buildings are contaminated by soluble salts in varying degrees. The crystallization of salts in porous material under the surface will cause damage to the materials. If the salt crystallizations are likely to aggravate the degradation of the materials, two treatments are possible: (i) stabilization of the environmental conditions; (ii) the extraction of salts from the object.