Water and its interaction with porous inorganic building materials: Fid-Bau Portal

Water and its interaction with porous inorganic building materials

Wendler, E. / Charola, A.E.

Water has long been identified as one of the key factors in the deterioration of porous inorganic building materials. Therefore its behaviour with regards to these materials is fundamental. Although this area has been studied exhaustively by scientists in various disciplines, there has been a lack in trying to bring together, and to present a comprehensive and comprehensible image of the reason for the interaction water has with these materials. It has been the aim of the paper to put forward a broader picture of the water-porous inorganic material interaction, rather than focusing on the mathematical expressions that have been developed to describe them. Starting with the abundance of oxygen in both the lithosphere and the atmosphere, to its particular electronic configuration that allows the formation of hydrogen bridges that are the reason for the anomalous behaviour of water, i.e., the expansion it suffers upon freezing. The balance of the cohesive forces between water molecules and the adsorption that water has for mineral surfaces are at the origin of all the observed occurrences in the water-porous inorganic material interaction. The adsorption of water on the pore surfaces leads to the formation of ordered water structures. These structures play an active role in the transport of liquid water through capillaries and lead, in smaller pores, to the condensation phenomena. In summary, water can be in a totally disordered state as in water vapour, in a labile order as in liquid water, as a short range ordered structure when adsorbed on a mineral surface and as a totally ordered structure as ice.