Fabrication and application of an innovative low cost-efficient polymer nano-composite as concrete protective coating

Recently, asphaltic polyurethane coatings were prepared by mixing asphalt with limited ratios of polymers, but this method has many disadvantages. So the novel contribution of this work is using the in situ polymerization method to prepare asphaltic polyurethane nano-silica (As/PUR-NS) coatings. The novelty of this work is using asphalt as one of the polyurethane raw materials by mixing it with castor oil , and the obtained mixture acts as a mixed polyol (80% asphalt and 20% castor oil). As/PUR-NS coatings were prepared with a 1.3 NCO/OH molar ratio by reacting 4,4′-diphenylmethane diisocyanate (MDI) with the prepared mixed polyol , and then NS was added with different ratios of 0.5, 1, 1.5, 2, and 2.5%. The prepared coatings were characterized by determining both curing time and physico-mechanical characteristics and then applied to concrete cubes as a protective coating. The uncoated and coated concrete cubes were tested with regard to water absorption, contact angle, and chloride diffusion, as well as their durability against both sulphate and chloride attacks. The study revealed the high efficiency of concrete coated with a low-cost, eco-efficient, novel protective coating.