Fatty acids as hydrophobizing agents for granular materials

Abstract

Hydrophobic (or non-wetting, water repellent) soils have a low affinity for water. The importance of soil hydrophobicity has already been recognized due to its effect on soil hydraulic properties and potential applications in ground-related constructions. The treatments coat soil particles with synthetic or natural substances (e.g. organosilane and fatty acids). Fatty acids such as stearic acid have been used widely to induce hydrophobicity, because of their similar composition to natural hydrophobic substances in soils and with the advantage of being compatible with the environment. Following an introduction to hydrophobic soils, this paper reviews fatty acids that can be employed to induce hydrophobicity in granular materials and the treatment methods used to achieve it. Results are provided for a vegetation oil (flaxseed oil) on hydrophilic sands, revealing an increase in hydrophobicity with the addition of the flaxseed oil.