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Moisture diffusion in and capillary suction of integral water repellent cement based materials
All properties of concrete depend on moisture content. Pre-dried concrete absorbs comparatively big amounts of water quickly by capillary action if the surface gets temporarily wet or is permanently in contact with liquid water. Capillary suction of water is an efficient mechanism for transport of dissolved salts such as sulphates, chlorides, and ammonium compounds into the porous structure of concrete. This ion migration is known to be at the origin of the most frequently observed deterioration of reinforced concrete structures in aggressive environment. It has been shown recently that capillary action can be practically suppressed by surface impregnation of concrete with liquid silanes. In practice and for some cases at least, it would be beneficial, if the entire volume of a structural element could be water repellent and not only the areas close to the surface. This goal can be reached, in principle at least, by adding silane emulsion to the fresh mix of cement based materials. Materials produced in this way may be called integral water repellent concrete or mortar. The contribution presents results obtained for the moisture diffusion coefficients of the first drying process as determined by inverse analysis on the basis of drying data. Capillary suction of control and integral water repellent concrete has been determined. As expected, capillary suction of integral water repellent concrete is significantly reduced as compared to similar control concrete, prepared without the water repellent agent. The protective effect of surface impregnation of concrete, however, is superior. Nevertheless, service life of concrete structures in aggressive environment can be extended substantially by using integral water repellent concrete instead of normal concrete.
Moisture diffusion in and capillary suction of integral water repellent cement based materials
All properties of concrete depend on moisture content. Pre-dried concrete absorbs comparatively big amounts of water quickly by capillary action if the surface gets temporarily wet or is permanently in contact with liquid water. Capillary suction of water is an efficient mechanism for transport of dissolved salts such as sulphates, chlorides, and ammonium compounds into the porous structure of concrete. This ion migration is known to be at the origin of the most frequently observed deterioration of reinforced concrete structures in aggressive environment. It has been shown recently that capillary action can be practically suppressed by surface impregnation of concrete with liquid silanes. In practice and for some cases at least, it would be beneficial, if the entire volume of a structural element could be water repellent and not only the areas close to the surface. This goal can be reached, in principle at least, by adding silane emulsion to the fresh mix of cement based materials. Materials produced in this way may be called integral water repellent concrete or mortar. The contribution presents results obtained for the moisture diffusion coefficients of the first drying process as determined by inverse analysis on the basis of drying data. Capillary suction of control and integral water repellent concrete has been determined. As expected, capillary suction of integral water repellent concrete is significantly reduced as compared to similar control concrete, prepared without the water repellent agent. The protective effect of surface impregnation of concrete, however, is superior. Nevertheless, service life of concrete structures in aggressive environment can be extended substantially by using integral water repellent concrete instead of normal concrete.
Moisture diffusion in and capillary suction of integral water repellent cement based materials
Feuchtediffusion und Kapillaransaugung von durchgängig wasserabstoßenden Baustoffen auf Basis von Zement
Zhang, P. (author) / Wittmann, F.H. (author) / Villmann, B. (author) / Zhao, T.J. (author) / Slowik, V. (author)
2008
13 Seiten, 7 Bilder, 2 Tabellen, 15 Quellen
Conference paper
English
Preparation and Characteristics of Integral Water Repellent Cement-Based Materials
| Tema Archive | 2011
Preparation and Characteristics of Integral Water Repellent Cement-Based Materials
| British Library Online Contents | 2011
Silane and siloxane based "integral water repellent" for cementitious materials
| Tema Archive | 2011