Overview
So far water repellent treatment has been very controversial for practical applications. The reason for this is mainly the fact that there is no rational basis for application technologies. Within this project the rate of penetration and the corresponding penetration depth is to be studied as function of the quality of concrete. The aim of the project is to define clear requirements for the application of water repellent agents. A reliable test method is to be developed in order to be able to determine penetration profiles of water repellent agents.
It has been shown so far that the penetration depth of the water repellent treatment is most essential for a long-term performance. Sufficient penetration depth can be achieved only if the surface is in contact with the water repellent agent for a long enough period. Today there are at least 3 alternatives to achieve this aim:
(a) use of a Silane cream,
(2) 5-8 times spraying with an interval after the 2 first treatments,
(3) application of the agent from a box attached to the surface.
A basis for engineering design of surface treatment with water repellent agents is to be established.
At the same time a major aim is to develop a system for quality control of the treatment.
Funding
Results
The essential parameters for a successful water repelent treatment were determined through extensive investigations on structures in use. It could be shown that quality of concrete and distribution of humidity proved highly influential whereas the age of concrete and the type of cement being used merely played a minor role.
Technical Implications
It could be shown that wet in wet application though quite frequent in practice often did not satisfy the requirements. Preparatory water repelent treatment constitutes an adequate measure of surface preparation and significantly increases the effective penetration.
Other results
S.J. Meier, F.H. Wittmann, Notwendige Kriterien für eine Tiefenhydrophobierung, in Werkstoffwissenschaften und Bauinstandsetzen V, Aedificatio Verlag, D-Freiburg, p. 751-762 (1999)
Gerdes, A., Meier, S.J. und Wittmann, F.H., A New Application Technology for Water Repellent Surface Treatment, Water Repellent Treatment of Building Materials, Proceedings of Int. Conference on Water Repellent Treatment of Building Materials, Hydrophobe II, ETH Zürich, F.H. Wittmann (ed.), Aedificatio Publishers, Freiburg, 217-230 (1998)
Meier, S.J. und Wittmann, F.H., Entwicklung einer Zweikammer-Messzelle zur Bestimmung der kapillaren Flüssigkeitsaufnahme, in Internationale Zeitschrift für Bauinstandsetzen, 5, 177-186 (1999)
Meier, S.J. und Wittmann, F.H., Notwendige Kriterien für eine Tiefenhydrophobierung, 5. Internationales Kolloquium Werkstoffwissenschaften und Bauinstandsetzen- „MSR `99“, Aedificatio Publishers, Freiburg, 751-762 (1999)
Moetsch, H.A., Meier, S.J., Gerdes, A. und Wittmann, F.H., Eindringtiefe eines Hydrophobierungsmittels als Funktion der Qualität, des Feuchtigkeitsgehaltes und des Alters des Betons, Internationale Zeitschrift für Bauinstandsetzen, 5 289-306 (1999)
Meier, S.J. und Wittmann, F.H., Influence of Quality of Concrete, Moisture Content and Age on Penetration Depth of Water Repellent Agents, Proceedings of Hydrophobe III - 3rd Int. Conference on Surface Technology with Water Repellent Agents, Hannover, K. Littmann und A.E. Charola (Editors), Aedificatio Publishers, Freiburg, 123-132 (2001)
Meier, S.J., Martinola, G. und Wittmann, F.H., An Approach for Monitoring Impregnated Reinforced Concrete Structures Exposed to Severe Chloride Exposure, Proceedings of Hydrophobe III - 3rd Int. Conference on Surface Technology with Water Repellent Agents, K. Littmann und A.E. Charola (eds.), Aedificatio Publishers, Freiburg, 143-154 (2001)
Wittmann, F.H., Meier, S.J. und Gerdes, A., Hydrophobieren von Betonoberflächen, Proceedings zu Anwender-Workshop zur Nutzung der Neutronenradiographie, Paul Scherrer Institut, Villigen (CH), 36-39 (2001)
Meier, S.J. und Wittmann, F.H., Influence of Quality, Age and Moisture Content of Concrete on the Penetration Depth of Water Repellent Agents, in Internationale Zeitschrift für Bauinstandsetzen, 8 (2002)
Meier, S.J., Grundlagen und Möglichkeiten einer Hydrophobierung von Betonbauteilen, Dissertation ETH Zürich, Diss. ETH Nr. 14811 (2002), erschienen auch al