Scientists in China have developed what they claim is a self-cleaning concrete that is strong and durable. Researchers from the University of Science and Technology of China, led by Prof. Xin Xu, wanted to see if they could replicate the hydrophobic (water-repelling) features found in nature in a building material. The results of their research has been published in the journal ACS Applied Materials & Interfaces.
There are many examples of self-cleaning hydrophobic surfaces in nature. Many types of leaves are hydrophobic, allowing raindrops to roll off of the leaf carrying dust and debris with them. There are some animals that have hydrophobic features, allowing water to roll off of their skin or letting them traverse across the surface of ponds and streams. A building material that possesses these properties could save immense time and labor in homes and businesses and be used to create bacteria-resistant surfaces for healthcare settings such as hospitals.
Previous attempts at adding hydrophobic materials to concrete haven’t been entirely successful. When mixed into wet concrete, the materials have compromised its strength upon drying. When added as a surface coating, it gets scratched off or worn away over time.
The researchers led by Xin Xu attempted to solve these issues by adding oil, an emulsifier and a hydrophobic silicone polymer called polydimethylsiloxane (PDMS) to wet concrete. When the concrete dried, it left pores coated with PDMS on the concrete. The resulting concrete was lightweight, mechanically strong, and was able to repel all sorts of liquids including beer, soy sauce, coffee and dyes. None left a stain. The self- cleaning properties remained even after mechanical grinding, heat treatment, and exposure to chemicals.
The researchers acknowledged funding from the National Science Foundation of China, the China National Petroleum Corporation-Chinese Academy of Sciences Strategic Cooperation Research Program and the Open Foundation of the State Key Laboratory of Advanced Refractory Materials in their paper.