INFLUENCES OF DICHLORODIMETHYLSILANE TREATMENT ON SOIL HYDROPHOBICITY, THERMAL CONDUCTIVITY, AND ELECTRICAL CONDUCTIVITY

Abstract

Soil water repellency occurs in a wide range of conditions, and it influences heat, water, and solute transport in soils. Dichlorodimethylsilane (DCDMS) has been used as a hydrophobizing agent to create waterrepellent soil materials by mixing the chemical with wettable soil samples. Little is known about how DCDMS treatment affects soil thermal and electrical properties. This study examines the influences of DCDMS treatments on soil water repellency, thermal conductivity, and electrical conductivity. Laboratory studies were performed on DCDMStreated soil samples with different degrees of water repellency. Soil thermal conductivity (1) and bulk electrical conductivity (Ab) were determined with the heat pulse method and time domain reflectometry technique, respectively, on repacked soil cores of various water contents. The results showed that DCDMS was able to hydrophobize soil samples, but reduced 1 and increased Ab at water contents greater than a critical value compared with wettable soil samples. Our analysis indicated that the increase in soil Ab was a result of salt dissolution from solid particle surfaces, which probably altered the hydration state of the solid particles. We concluded that DCDMS was effective in producing water-repellent soil samples, but the treatment also changed other soil properties, such as 1 and Ab. (Soil Science 2008;173:425‐432)