Fabrication of self-cleaning fly ash/polytetrafluoroethylene material for cement mortar spray-coating

Dust pollution has adverse effects on the esthetics and service life of buildings and also increases maintenance costs. The use of a superhydrophobic surface is a promising practice to reduce the accumulation of dust and facilitate the cleaning of surfaces. In addition, a superhydrophobic surface improves the anti-corrosion properties of material, with a reduction in water penetration of concrete. Therefore, this paper presents the fabrication of a self-cleaning fly ash (FA)/polytetrafluoroethylene (PTFE) material for cement mortar spray-coating. To study the self-cleaning properties, the water contact angle and sliding angle of the surfaces were measured. The surface coated with PTFE and 10% FA shows a contact angle of 147 degrees, which indicates a hydrophobic surface, and has self-cleaning properties with a sliding angle of less than 10 degrees. Micro-papillae can be observed on the coated surface and play an important role in preventing water from penetrating the substrate. Ground bagasse ash was used as dust to study the self-cleaning properties. The rolling of a water droplet on the dust-coated surface results in the cleaning of the coated surface, as the dust collects on the droplet surface. The cleaning process can also be achieved with the use of seawater and hydrochloric acid solution droplets. Thus, the FA/PTFE self-cleaning material has the potential to be used for cement mortar coating. (C) 2020 Elsevier Ltd. All rights reserved.