Assessing a Sand Clay Liner Material for Protecting Highways and Road Shoulders

The damage and distress caused to highways and roads within areas of high swell potential are of great concern in the design of infrastructure projects. The Subgrade is a significant part of the road structural systems. Variation in moisture content due to seasonal weather fluctuation and flooding could result in harming the road foundation support. This is because the capacity and consistency of the support provided by the subgrade are dependent on the soil type, density, and moisture contents. Different rainfall pattern and intensity from one place to another makes the subgrade response more complicated. The common approach to the water or moisture influence on road structures is to prevent moisture or water from entering the systems. However, in the case of severe flooding, it will not be easy to divert all the flood water away from the road structures. Therefore, efficient protection is required. This study is aimed at assessing clay sand liners of variable mix designs to be constructed as a dressing layer along the shoulder or within the body of the shoulder and extending beyond the foot of the slope. Materials of highly expansive clay from Saudi Arabia were mixed with fine to medium sand at variable proportions to introduce the required protection liners. Characterization tests and hydraulic conductivity tests were performed. Relationship between hydraulic conductivity and clay content was obtained and compared to other studies. Compressibility was obtained from the void ratio and vertical stress relationship. Designs were proposed for specific section geometries and shoulder slopes.