Weathering and deterioration

Abstract

It is generally assumed that stone is one of the most durable materials because it is compared to weaker building materials, such as wood or mud. But stone can deteriorate, and many factors will affect it. The nature of the stone is critical in determining its resistance to the various deterioration factors. The most important one, salt, was identified by Herodotus, nearly two and a half millennia ago. However, salt by itself is not damaging; it requires the presence of water for its aggressiveness to become evident. And water is needed for biocolonization to occur, for freeze-thaw phenomena, and for wet-dry expansion. Control of this single factor can decrease the deterioration potential of a stone and any structure built from it significantly. This chapter aims to present a review of the most important deterioration processes and their effect on the various types of stones and rocks used by man. Among them are thermal effects, the influence of moisture, both as water vapor and in liquid state, the presence of salts, and the damages that can be expected from biocolonization. This chapter also aims at identifying the areas where more research is needed to understand the actual deterioration mechanism of the various factors.