Performance evaluation of concrete coatings

Abstract

The use of surface coatings to minimize concrete deterioration, mainly due to reinforcement corrosion, is widespread. However, with the wide range of coatings available in the market it becomes extremely difficult to choose the right type, since coatings of similar generic types may exhibit considerably different properties. Further, the performance of surface coatings under the environmental conditions prevailing in the Arabian Gulf is not very well documented.

The study was conducted to evaluate the performance of concrete surface coatings under conditions simulating those of the Arabian Gulf.

Based on a survey of the concrete coatings available in the market, five generic types of coatings, namely, acrylic coatings, polymer emulsion coatings, epoxy coatings, polyurethane coatings and chlorinated rubber coatings were selected to evaluate their performance under aggressive environmental conditions.

The selected coatings were applied on concrete/mortar specimens of suitable size in accordance with the manufacturer guidelines and tested to evaluate their performance. The results of the experimental program indicated that both epoxy and polyurethane coatings performed better than the other coatings in almost all the exposure conditions evaluated in this study.

Based on the results of this study, guidance for selection of coatings appropriate for the service conditions has been provided. Performance criteria for evaluation of concrete coatings have also been suggested. Further, the experimental data was utilized to calculate the chloride and cabonation diffusion coefficients and model was suggested to evaluate the useful service life of a reinforced concrete structure coated with the selected coatings.