Thermal and electrical properties of water-repellent sands

The behavior of water-repellent soils has been less concerned in spite of the importance of engineering significance compared to the other characteristics of soils. In general, the surface property of soils in natural state is recognized as easy to wet and this concept has been applied to unsaturated soil mechanics. However, there are also water-repellent soils (hydrophobic) generated naturally or produced artificially. The thermal and electrical conductivity are typical indices to assess physical behavior of materials associated with surface wettability. This research presents thermal and electrical properties of wettable and water-repellent sands in unsaturated condition. The wettable sands are in its natural state and the water-repellent sands are chemically treated using organic silane. The microscopic observation using the scanning electron microscopic and the atomic force microscopic images confirms the existence of homogeneously grafted organic materials on the silicate mineral surface. Prepared materials are used in the thermal and electrical experimentations with varying degree of saturation. The transient plane source is used for the measurement of the thermal conductivity. The two-electrode system is selected in the electrical conductivity measurement. The surface wettability that affects the spatial distribution of water in pore space causes the noticeable difference of thermal and electrical properties in two materials.