Accelerated weathering of hydrophobized sands

Abstract

Hydrophobized sands have been suggested as materials for hydraulic barriers in infrastructure. When placed at the interface ground–atmosphere, environmental factors such as temperature and rainfall are expected to impact their performance and impair their durability. This study uses accelerated weathering tests to investigate the degradation of industrial sands functionalized with Tung oil, heated Tung oil and dimethyldichlorosilane to render them hydrophobic. Laboratory samples were subjected to thermal ageing, water immersion, cyclic wetting–drying and cyclic freezing–thawing and analysed for their hydrophobic degradation (magnitude and persistency) including controlling mechanisms via surface imaging and analysis. The results revealed that (1) elevated temperature and prolonged water immersion degraded hydrophobicity, albeit with differences between the coatings: dimethyldichlorosilane-treated sands were stable under thermal ageing; (2) a greater concentration of hydrophobizing compounds could minimize hydrophobic degradation during cyclic wetting–drying; (3) freezing–thawing had a negligible effect on hydrophobicity. In order to minimize their degradation, these results suggest that hydrophobized sands can be synthesized by adjusting the hydrophobizing compound and its concentration to suit a specific application.