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Use of Enhanced Lateral Drainage Geotextiles in a Pavement Founded on Expansive Clays

Expansive clay soils are a major source of distress in pavements founded on them, responsible for billions of dollars’ worth of damage every year in the United States alone. Moisture migration in clays is directly responsible for the volumetric changes in expansive clays, which cause the pavement distresses, typically in the form of longitudinal cracks. Newly developed enhanced lateral drainage geotextiles aim to minimize expansive clay-related damages by providing in-plane enhanced drainage to control the differences in the moisture content (and consequently differential volume changes) within the clay soil. In order to evaluate the performance of enhanced lateral drainage geotextiles in a pavement section founded on expansive clays, eight 500 ft (152 m) long test sections were constructed along State Highway 21 (SH-21) near Bastrop, Texas, USA, in 2013. Four different geotextiles were installed, including one with enhanced drainage capabilities, two with conventional woven geotextiles, and one with a conventional nonwoven geotextile. Each test section was equipped with sensors to monitor moisture within the expansive clay subgrade. Regular site visits were conducted after construction of the sections to retrieve moisture data and conduct condition surveys to document pavement distresses. Additionally, total station surveys were conducted to monitor vertical displacements and resulting fluctuations in the shrink/swell behavior of the soil. Results indicate that enhanced drainage geotextiles facilitate equilibrating the moisture content within the underlying subgrade soils, unlike conventional geotextiles that did show significant differences in subgrade moisture content within the pavement section.