Optimization of water repellency in soils for geotechnical applications

ABSTRACT

Applying organo-silanes (OS) as water-repellent additives can enhance soil properties, crucial for use as moisture barriers in infrastructures like roads, landfills, and tunnels. This study used four soil samples and glass beads, treated with three OS products at dosages from 1:1 to 1:1000. Laboratory tests included contact angle, water drop penetration, and breakthrough pressure on 216 samples. Results showed increased hydrophobicity with higher OS dosages, with contact angles over 110° and Water Drop Penetration Test times above 3600s. However, effectiveness plateaued at certain dosages, indicated by electrical conductivity and pH changes. The primary factors (94.6% influence) were soil type, OS product, dosage, and drying condition, while reaction time, and leaching/washing had a minor impact (5.4%). Treated soils could sustain a hydrostatic head of up to 17 kPa. These insights aid in optimizing water-repellency treatments for soil performance and infrastructure durability in geotechnical applications.

KEYWORDS:

• Hydrophobic
• contact angle
• breakthrough pressure
• grain size
• water-repellency

Acknowledgments

This work was part of a larger experimental campaign, inclusive of field, laboratory, and numerical aspects as funded by the U.S. National Science Foundation (Award #1928813). Soils were provided by the Iowa Highway Research Board (Keokuk County), the North Carolina Department of Transportation (Ashe County), and the Cold Regions Research and Engineering Laboratory, a U.S. Army Corps of Engineers, Engineer Research and Development Center. The authors would like to appreciate Mya Mitchell, an undergraduate student in the Department of Civil and Environmental Engineering, UNC Charlotte, and Cadet David Ragan, from the U.S. Military Academy in West Point who carried out tests on the project as part of their summer research internship and Advanced Individual Academic Development (AIAD) project, respectively. We would also like to thank the reviewers for taking the necessary time and effort to review the manuscript. We sincerely appreciate all their valuable comments and suggestions, which helped us in improving the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated during and/or analysed during the current study are available from the corresponding author upon reasonable request.

Additional information

Funding

The work was supported by the National Science Foundation [1928813].