Treatment for Rising Damp and Natural Hydrodynamic Equilibrium in Masonry Walls

Abstract

. The water absorption, in the Historic Heritage Restoration, through porous materials of the different constructive elements, is certainly one of the factors that constitute the basis for most pathologies and degenerative phenomena on plastering and masonry walls. Particularly, the most critical humidity comes from the soil, because it contains salts (chlorides, sulphates, nitrates). Those salts impregnate the masonry and unleash humidity rises up to several meters. Humidity varies the physical and chemical behaviour of the wall, increasing the thermic conductivity and limiting the isolation power. In addition, due to surface crystallization of the salts, early disintegration of the building materials and rapid destruction of the wall are generated. A wall saturated with water diminishes its isolation power and favours the formation of mould and bacteria, worsening the healthiness of the environments and the well-being of the people who habit them. In nature, a natural hydrodynamic balance is established between the water absorbed by building materials through capillarity and osmosis, and the water transferred to the atmosphere through evaporation. The constant components within this equilibrium are the absorption of water through capillarity and osmosis of the building materials, and the chemical nature of the aqueous solution absorbed. The variable components are the temperature and relative humidity of the atmosphere. The evaporation surface, composed by masonry mortar, plastering, scraping and painting are the