Laboratory Drainage Performance of a New Geotextile with Wicking Fabric

Geotextiles are commonly used in road design to provide mechanical and hydraulic functions due to their high strength and porous properties. The long-term performance of a soil–geotextile system is not solely determined by the soil or the geotextile itself; it also depends upon their interactions. Emphasizing only the geotextile mechanical functions cannot solve all engineering issues. The performance of a soil–geotextile system can be disappointing when the soil moisture content increment is small. Capillary water exists in a variety of soils and can be difficult to drain under unsaturated conditions. Unfortunately, the existing subsurface drainage design methods can only deal with free water (water that flows under the influence of gravity) and conventional capillary barriers cannot wick water out of pavement structures, resulting in overestimating the long-term performance of the pavement. A new geotextile with wicking fabrics has the potential to solve this issue. Preliminary laboratory and field tests have proved its effectiveness to wick both gravitational and capillary water under unsaturated conditions. This paper further explores some potential concerns regarding the future extensive applications of this new geotextile. A series of lab tests were performed to study the working mechanism of the new geotextile, evaluate its drainage efficiency, and assess the effects of splice and clogging on the drainage performance of the new geotextile. Test results indicate that the new geotextile can effectively drain both gravitational and capillary water out of pavement structures; however, splices may reduce the drainage efficiency. The clogging effect should not be a major concern for the long-term performance of the new geotextile in soils with fine content lower than 14.5%.