Green and Sustainable Superhydrophobic Phosphogypsum Mortar Coating with Self-Cleaning Properties and Water Resistance

Abstract

Phosphogypsum (PG) is a solid waste generated by phosphate fertilizer industries that is currently used in concrete materials. However, adding PG to concrete usually results in reducing its water resistance and corrosion resistance. This paper presents a new method of applying PG to concrete to improve its water resistance. In this paper, a green superhydrophobic PG (SPG) coating was prepared using modified PG as a hydrophobic medium and cement as the bonding material. The contact angle between the superhydrophobic phosphogypsum coating (SPG coating) and water was 156°, and the coating reached a superhydrophobic state with good self-cleaning ability. Even when sandpaper was used to polish the coating, the water contact angle of the coating was still greater than 150°, indicating that the coating had good wear resistance. In addition, the results of water absorption and electrochemical experiments indicated that mortar coated with SPG had better water resistance and corrosion resistance than ordinary mortar. The SPG coatings with water resistance, wear resistance, and self-cleaning properties have potential applications in building exterior walls.