Decay factors and patterns of stones in open-air historical sites built of carbonate sedimentary stones

The number of historical open-air sites built of stone are relatively limited in comparison to the other historical artificial in Iran, but these sites include great significance in terms of value, historic and their knowledge of past. Since these stone poen-air sites are generally about two thousand years old, they have been exposed to decay factors for a long time. Many information and data on the types of decay factores and their patterns are scattered in the articles and books generally available in English which their access to experts in the field of conservation and restoration is limited. In this study, we attempted, through purposeful data from research on the open-air sites and monuments, to effectively address all aspects of the deterioration of carbonate sedimentary stones which constitute the majority of Iran’s sites. In this way, using library references, environmental factors and common decay patterns in similar climate and industrial conditions are discussed. It has become clear from studies that, contrary to the impression, “environmental factors” are not only the factors in the deterioration of sedimentary stones, but also the physical and chemical properties of the stone (Intrinsic problems) are also very important in the term of decay. Among the chemical and physical decay factors, chemical factors in deterioration are more important because the lead to the dissolution or alteration of the nature of the stone.