Quantifying Soil Moisture Reduction by Wicking Geotextile to Minimize Pavement Distresses

Excessive moisture in pavement foundations including base courses and subgrade is one of the major causes for pavement distresses, which often pose safety risks to vehicles and drivers and increase the cost for maintenance and reconstruction. Moisture can weaken pavement foundations and become a source for freeze-thaw problems in cold regions, which accelerate the deterioration of pavements with time. Therefore, pavement drainage is critical to pavement performance. Typical drainage systems are effective for saturated soils but become less effective or ineffective for unsaturated soils. Wicking geotextile that contains deep-grooved fibers can generate suction when in contact with water and reduce moisture in unsaturated soils. However, the effectiveness of the wicking geotextile in reducing moisture depends on several factors including the percent of fines in soils. So far, no simple test method is available to evaluate the effectiveness of the geotextile in reducing moisture in soils including those with fines and no fine content limit has been established for the wicking geotextile to be effective. The proposed research is to develop a simple soil box test to quantify the effectiveness of the wicking geotextile in reducing moisture in sands at different fine contents and distances from the geotextile as compared with the conventional geotextiles. The soil box tests will first determine field capacities of silty sands at different fine contents and then evaluate moisture reduction by geotextiles by measuring moisture contents at different distances from the geotextile location at different times. These tests will determine the amount of moisture reduction and the distance of influence, and the fine content limit for the geotextile to be effective. The objective of this research is to develop a simple test method to quantify soil moisture reduction by geotextile and provide guidance for its use in sands with fines.