Quantifying and Incorporating the Benefits of Wicking Geotextile into Pavement Design

Abstract

Geotextiles have been widely used in pavement systems for reinforcing base and subgrade layers. However, the capillary break effect minimizes the benefits of reinforcement due to excess pore-water pressure accumulation at the soil–geotextile interface. In contrast, the wicking geotextile has the ability to provide superior lateral drainage ability and overcome the limitations of nonwicking geotextiles. Both field and laboratory tests have proven the efficiency of the wicking geotextile to dehydrate road embankments. However, the benefits of wicking geotextiles have not been considered in the existing pavement design methods. This paper aims at comparing the drainage performance of pavement structures without any reinforcement, with a nonwicking geotextile, and with the wicking geotextile. Firstly, a coupled hydromechanical model is proposed to predict pavement performance under saturated and unsaturated conditions. The effective resilient modulus data were obtained from the numerical model, and the methodologies of incorporating the benefits of the geotextiles into the design guides are discussed in detail. Simulation results indicated that by using the wicking geotextile, the thickness of the base course could be reduced by nearly 50% based on a standard US design guide, and the rutting depth reduced by 35% according to a standard pavement design guide. However, the nonwicking woven geotextile caused a detrimental effect to the pavement structure due to the capillary break effect, especially in a situation with a shallow water table.