Comprehensive Material Characterizations of Pavement Structure Installed with Wicking Fabrics

Abstract

When a road is constructed, soils within the embankment are often compacted at the optimum water content to achieve the best performance. The postconstruction water content tends to increase with time due to capillary action, precipitation infiltration, and water condensation. Because soils are sensitive to water content variations, a slight water content increase will cause a significant reduction in soil moduli and a dramatic increase in permanent deformation under cyclic loading. Materials with large pores, such as granular materials and nonwoven geotextiles, are commonly used for the drainage of gravitational water under a saturated condition, but not for the drainage of capillary water under an unsaturated condition. Therefore, the excessive water in the soil accelerates the deterioration of the road with time. Recently, a new geotextile with wicking fibers, which can drain both gravitational and capillary water under saturated and unsaturated conditions, has been developed. Several field applications have proven its effectiveness in dehydrating the road embankment. This paper aims to quantify the benefits of the new geotextile in terms of water removal. First, comprehensive laboratory tests were performed to characterize the properties of the soil, the new geotextile, and the soil-geotextile interactions. Second, the working mechanism and functional range of the new geotextile were determined and the drainage ability of the soil-geotextile system was quantified via numerical simulations. The wicking fabric functions as an effective drainage material to hold and transport capillary water in the in-plane direction. The soil-geotextile system is able to reduce the water content of the base course by 2.2% from the optimum value, and the corresponding resilient modulus can be increased by 2–3 times.