Traditional coatings as protection of portland cement concrete against carbonation

Abstract

Reinforced concrete is usually subjected to carbonation attack. Although it is a slow development pathology, the consequences can be high, precisely in the places with greater human, residential or industrial occupation. To make matters worse, carbon dioxide concentration in the atmosphere has been increasing due to the impact of climate changes and also to the growth of number of large cities. One of the ways to increase the resistance to carbonation attack may be through the application of concrete coatings. In fact, many current constructions have a protective skin on the concrete, often ignored in the durability design project. For these reasons, this research has looked into the efficiency of the coatings when applied on concrete. Priority was given to traditional unpainted coatings, with cementitious base, hydrated lime or both. A coating based on fly ash and a thin coating of cement were also tested. All of them were applied in an ordinary Portland cement concrete. Accelerated carbonation tests were performed and the results were excellent. It was observed that the performance of the coated concretes was, on average, about 65% better when compared to the uncoated concrete.