Nano/stearic acid superhydrophobic coatings on concrete with high chemical and microbial stability

This study aims to develop and ascertain cost-effective, highly chemically stable, superhydrophobic, antimicrobial coatings to enhance the durability of concrete in aqueous and wastewater environments, which are typically challenged by microbial contamination, chemical erosion, and long-term exposure to corrosive ions. For this purpose, the performance of five organic coatings modified with stearic acid (STA) and nanoparticles (CuO, SiO2, and TiO2) was assessed in terms of self-cleaning, water absorption, chemical resistance, stability in chloride environments, resistance to sulfuric acid, antimicrobial properties, durability against UV radiation, and mechanical strength. The results revealed that the applied coatings led to a 57.42% reduction in water absorption compared to control concrete and provided effective self-cleaning behavior. The modified concrete revealed remarkable chemical stability in different pH environments, 27 wt% NaCl solution, and sulfuric acid solution, such that following immersion in sulfuric acid, the water contact angle (WCA) was still maintained above 130°. Further, two coatings, STA/TiO2 and STA/CuO indicated excellent resistance against microorganisms present in wastewater. These coatings also provided high mechanical durability and adhesion against UV radiation, abrasion cycles, and tape peeling tests. Overall, the results demonstrate that the developed coatings can be an efficient and economical option to boost the durability and performance of concrete in industrial applications and corrosive environments.