Preparation, characterisation, and anti-icing properties of superhydrophobic coatings on asphalt mixture

In order to reduce the safety risk caused by icing on asphalt pavement, we propose a new method to prepare a superhydrophobic coating (SHC) on asphalt mixture surfaces for anti-icing purposes. The nano-SiO2 particles modified by a coupling agent (KH550), and oxysilane were sprayed on the asphalt mixture surfaces to prepare the SHC. Fourier transform infra-red spectra prove that Si-O-Si and C-H are the main components of the superhydrophobic materials, and the coupling agent has a good cross-linking effect. SEM images reveal that SHCs have a micro nano-binary composite structure, and show excellent super-hydrophobicity. Moreover, when the spraying amount of the SHC with nano-SiO2 (30 nm), KH550 (4 ml), MTMS (6 ml) and DMDS (4 ml) on asphalt mixture was 40 ml, the contact angle presented the highest value of 154.2 degrees. The anti-icing tests confirm that the SHCs can effectively delay the freezing time of surface water and decrease the adhesion force between the ice and the pavement. The simulated rainfall test verifies that the superhydrophobic properties of SHCs become worse after water washing. After 2 h of droplet impact, the contact angle of the SHC surface on asphalt mixture is still close to 150 degrees, and SHCs still have good hydrophobic properties.