Incorporating a new wicking geotextile in northern, low volume highways to mitigate pavement edge cracking

Longitudinal edge cracking is a widespread and costly safety concern for northern regulators, such as Yukon Highways and Public Works. The exact cause of longitudinal edge cracking in northern, low volume highways is not well understood. There are many factors that may be linked to cracking such as weak materials under the side slope toe, differential frost heave, oversteepened side slopes, concentration of moisture in road edge materials, and climate change. In an effort to prevent edge cracking in its low volume pavements, the Yukon Government partnered with FPInnovations and TenCate in 2015 and 2016 to construct two, instrumented, thin pavement test sites on the Campbell Highway near Watson Lake, Yukon. The test pavements were reinforced with a new geosynthetic product; instrumentation installed above and below the geotextile monitored roadbed moisture content and temperature. Mirafi® H2Ri is a high strength, woven, geotextile with hygroscopic, hydrophilic, and wicking properties that promote rapid drainage. It is anticipated that the geotextile will help prevent edge cracking by interrupting capillary rise from the subgrade, draining excess moisture from thawing layers, providing additional structural support, and confining road edge materials. Additional benefits may include the mitigation of rutting, cracking and pot holes associated with excess roadbed moisture. Activities in 2015 comprised site construction, and monitoring of moisture and temperature trends. The shoulders of the test pavement sections were consistently wetter than near centerline before and after paving. The geotextile, installed at the subbase-subgrade interface, reduced moisture in the subbase of both test pavements by up to 3%. In 2016, activities included continuing to evaluate roadbed moisture control by the geosynthetic, and assessing how well the new pavement design controls edge cracking and other pavement distresses. This innovative research will provide knowledge to owners, designers, and maintainers of low volume northern roads about road construction solutions to mitigate pavement distress, improve safety, and decrease maintenance costs.

 

Key words: Edge cracking, Mirafi® H2Ri, geosynthetics, northern roads, low volume, instrumentation, design, drainage