Nano-engineered Superhydrophobic and Overhydrophobic Concrete

The use of superhydrophobicity and overhydrophobicity in cementitious materials can lead to improved durability performance. Ingress of water with dissolved chemicals can have detrimental effects on the performance of cementitious materials. Additionally, reducing the amount of water and ice on concrete surfaces can improve the reduction of scaling, thereby preserving the pore system and integrity of concrete. The hydrophobic, overhydrophobic, and superhydrophobic surfaces can be realized by using particle deposition and siloxane coatings. Thin layers of such water repellant material can create a strong barrier to water. Another method to improve the durability of concrete is based on the addition of superhydrophobic admixtures of polymethyl hydrosiloxane emulsions and nano particles. These admixtures can produce a 3-dimensional volume hydrophobization by releasing hydrogen in alkali environments enabling the formation of air voids throughout a cementitious matrix. The walls of these voids are then coated with varying size particles producing the surface roughness required for superhydrophobicity. This paper compares different approaches and benefits of superhydrophobic concrete and discusses the improved durability properties and the future applications.