Performance evaluation of cement-based surface coatings

Concrete structures in aggressive environments are prone to a reduction in their design service-life due to one or more of the following causes: reinforcement corrosion, sulfate attack, chemical attack etc. In addition to utilizing a good quality concrete, protective measures, such as use of coated bars, and/or application of surface coatings, are now commonly utilized by the construction industry worldwide. Cement-based coatings are now widely used as they are considered to be safe from the point of view of preserving the alkaline nature of concrete pore solution. This paper presents results of an investigation conducted to evaluate the performance of cement-based surface coatings in environments commonly occurring in the field. The performance of selected cement-based surface coatings was evaluated by ascertaining their adhesion to the concrete substrate, crack bridging ability, chloride diffusion, moisture resistance, water permeability, carbonation diffusion, and chemical resistance. Best adhesion was exhibited by the epoxy-modified cementitious coating. Similarly, the chloride permeability was also the lowest in this type of coating. The crack bridging ability of the polymer modified cementitious coating was better than other cement-based coatings investigated in this study. These results indicate that epoxy modified cement-based coating provides adequate protection to concrete.