Hygro-thermal application conditions and adhesion

Coatings are designed to protect concrete against environmental aggression. Water is one of the aggressive parameters able to deteriorate the concrete structure. The objectives of this paper are to present the effects of water (i) during application of coating on the concrete substrate and (ii) pull-off test. Semi-permanent moisty state produced by absorption from the uncoated face, total immersion or diffusion of water from the back face of the substrate are analysed. Water vapour diffusion and influence of hydrophobic treatment are also investigated. A classification based on increasing influence of the tests and application conditions on adhesion is proposed and clearly points out the negative effect of capillary action from the uncoated face.