Salt Damage and Rising Damp Treatment in Building Structures

Abstract

Salt damage can affect the service life of numerous building structures, both historical and contemporary, in a significant way. In this review, various damage mechanisms to porous building materials induced by salt action are analyzed. The importance of pretreatment investigations is discussed as well; in combination with the knowledge of salt and moisture transport mechanisms they can give useful indications regarding treatment options. The methods of salt damage treatment are assessed then, including both passive techniques based on environmental control, reduction of water transport, or conversion to less soluble salts and active procedures resulting in the removal of salts from deterioration zones. It is concluded that cellulose can still be considered as the favorite material presently used in desalination poultices but hydrophilic mineral wool can serve as its prospective alternative in future applications. Another important cause of building pathologies is the rising damp and, in this phenomenon, it is particularly severe considering the presence of salts in water. The treatment of rising damp in historic building walls is a very complex procedure and at Laboratory of Building Physics (LFC-FEUP) a wall base hygroregulated ventilation system was developed and patented.

Conservation issues and chemical study of the causes of alteration of a part of the Stave Church in Hopperstad (Norway)

“…Such a combination could be different for the layers on the inside and outside of the church. There are generally several possibilities how salts can be brought into buildings: from air pollution, sea spray, atmospheric chemical reactions, reconstructions and renovations, de-icing agents, or rising damp [12,36,37].…”

“…The layer on Hopperstad Stave Church could possibly be harmful for the wood and metal in the long term, especially when the materials are unprotected by the tar. Salts, when in aqueous solution, can enter and move through porous materials thanks to capillary forces [36,39]. Salts inside building materials can absorb environmental moisture and dissolve.…”

“…When water evaporates, the salt crystallizes and can cause crystallization pressure inside the building material. During salt crystallization growth, high stresses can arise even in large pores in the materials, especially if the growing crystals are confined [12,32,36,[40][41][42]. Other damaging mechanisms can take place, too.…”

Contamination Assessment of Underground Water Around a Cemetery: Case study of Ayobo cemetery in Lagos, Nigeria

“…All water samples were found to be saline, as shown in Table 1. This high salinity in the water, leads to a rise in building and maintenance costs of structures, like roads and pipes, due to damage from the saline water [24]. On plants, high salinity may force the occurrence of reverse osmosis where the water in the roots of plants migrates into the underground water.…”

Forecasting the durability of reinforced concrete under conditions of microbiological corrosion

“…Since the salts are hydrophilic, they are usually hydrated, which leads to an increase in the water content of the porous material [16]. In addition, salt crystals may form during drying, causing the surface removal of layers of material [17]. Another harmful effect of salts is associated with the formation of large crystals that cause swelling [18,19].…”