Humidity factors affecting adhesion of coatings on concrete
Institut für Berufswissenschaften im Bauwesen, Universität Hannover, Herrenhäuser Strasse 8, Hannover 30419, Germany
The question of the durability of adhesion on moist and wet concrete surfaces addresses various matters to be dealt with in terms of engineering, building chemistry and building physics /1/. This paper looks at the topic from three different aspects.
Firstly there is the question as to how far current practice of measuring concrete moisture before the application of coatings is suitable for ascertaining the actual "coating compatibility" of the concrete. Different common methods are compared. An alternative procedure for measuring concrete moisture is presented which is capable of making precise statements on surface moisture.
The paper continues with a short summarised evaluation of several research projects. The study was based on four different big research projects with a large number of sample bodies which were all treated with 3 different epoxy resin formulations. The evaluation gives hints on humidity parameters before, during and after application.
Finally, the paper looks at the damage mechanisms which can limit the durability of adhesion in the presence of water. These include:
· Physical processes:
- Mechanical influences, gas pressure, osmotic pressure
· Interface reactions
- Bottom coating layer
- Saponification or hydrolysis in the coating material
- Top surface layer
- Decomposition of the bonding agent
· Ageing processes
Presentation: oral at E-MRS Fall Meeting 2005, Symposium G, by Klaus Littmann
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-25 09:48 Revised: 2009-06-07 00:44
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