Depending on their locations, certain of archaeological sites in Egypt (like elsewhere in the world) are severely suffering from the direct action and disruptive effect of salts. Many of Egyptian monuments contain soluble salts, either dispersed within stone and plaster or concentrated locally. Such salts are present as efflorescences forming different aggregates of crystals on the surface, as subflorescences forming crystalline aggregates beneath the surface, and as solutes on and within the walls. Depending on the forms and habits of salt crystals, Many kind of degradation were observed either on the stone surface as in Rameses temple, Taposirus temple, Qaitbay fortress, and Esna tempel or below the stone surface as in the Mortuary temple of Seti I in Luxor. Using the terminology of ICOMOS glossary, the main encountered degradations are; powdering, missing parts, erosion, delamination exfoliation, disintegration, alveolization and collapses.
Ahmed Sayed Shoeib (Tue,) studied this question.