Preparation and anti-icing properties of a superhydrophobic silicone coating on asphalt mixture

The formation of ice on pavement is a serious issue for driving safety. This paper proposes a new method of preparing a superhydrophobic silicone coating on asphalt pavement surfaces for the anti-icing purpose. The object of this paper is to investigate the anti-icing properties of the superhydrophobic silicone coating through the freezing time of water droplets and detachment forces of ice on asphalt mixture surfaces. In the preparation process of the coatings, an additive (layered double hydroxides, or LDHs) was initially modified by γ-methacryloxypropyltrimethoxysilane (KH550). Fourier transform infrared spectra and X-ray diffraction patterns were used to prove that LDHs particles have been successfully grafted by KH550. A special rubber (No. 107 room temperature vulcanized silicone rubber, or RTV) was then mixed with the modified LDHs to obtain the compound coating. Different amounts of solvents (No. 120 solvent naphtha) were sprayed on the compound coating to produce the micro/nano-scale rough surface. Contact angle test results show that the maximum contact angle of RTV and modified LDHs compound (RTV/LDHs) coating is 152.3° when 100 g/m2 of No. 120 solvent naphtha was sprayed on this coating. The freezing time of water droplet on the asphalt mixture with RTV/LDHs coating is 3 times longer than that on the asphalt mixture without coating. The ice detachment force on the asphalt mixture with RTV/LDHs coating decreases by 71% of that on the asphalt mixture without coatings. The vehicle traveling test displays that the RTV/LDHs coating has durable hydrophobic and anti-icing properties after the tire friction. From the above results, it can be concluded that this new superhydrophobic silicone coating makes significant improvements on the anti-icing properties of asphalt pavement.