Ceramics-Silikáty 55 (1) 79-84 (2011)

VERIFICATION OF THE EFFECT OF CONCRETE SURFACE PROTECTION ON THE PERMEABILITY OF ACID GASES USING ACCELERATED CARBONATION DEPTH TEST IN AN ATMOSPHERE OF 98% CO₂

M. Stehlík, J. Novák

Carbonation is one of the corrosion processes negatively influencing the properties of mature concrete. It is caused by a chemical reaction between carbon dioxide infiltrating the surface of a concrete structure and the minerals of the mastic cement. The surface of a concrete structure can be protected from the effects of atmospheric CO₂ by coating with modern waterborne epoxy dispersions. Out of the four types of dispersions tested (dispersion A – CHS Epoxy 200 V 55 + hardener Telalit 180, 2 layers; dispersion B – DOW XZ 92 533 + hardener XZ 92 441.01, 2 layers; dispersion C – CHS Epoxy 200 V 55 + hardener Telalit 180, 1st layer + Epostyl 217 V, 2nd layer; dispersion D – Epostyl 217 V, 2 layers), the type A solvent-based epoxy dispersion and the type C combination of the solvent-based and the solvent-free emulsions demonstrated the highest degree of protection of cement mortar. The effect and actual protection time was evaluated by means of the „accelerated carbonation depth test in 98% CO₂“.The correlation dependence found in the so-called ”accelerated test“ enables us to determine intervals of real time in the natural environment of 0.03% CO₂ corresponding to the intervals of accelerated exposition in 98% CO₂. It may be said that in the case of type A, type B, type C and type D coatings on higher-quality concretes, the coating would have to be renewed with an interval of maximum eight years.

Keywords: Carbonation of concrete, Epoxy dispersion, Diffusion, Phenolphthalein test, Concentrated 98% CO₂