The design of road structures in arctic regions has often to face the problem of cohesive subgrade in areas with high water table. In such areas the temperature in the winter season goes down even to -50°C and, due to saturation of the road embankment by the capillary rise of the ground water, the road structure completely freezes. In the summer season, when the temperature increases, the ice melts and becomes water again, producing high water flow that percolates into the foundation layers, producing the loss of bearing capacity and causing huge settlements and distresses in the road structure. This phenomena could occur in a single winter. The only way to avoid such problems is to prevent the frost heave phenomena. The paper aims to present an innovative drainage geocomposite, purposely engineered to create a capillary break for preventing the rise of groundwater into the road embankment. The capillary break is afforded by a hydrophobic nonwoven geotextile at the bottom face of the geocomposite; while at the top a standard nonwoven geotextile allows the water percolating through the granular layers of the road embankment to reach the draining core of the geocomposite, which has high thickness for both providing the required flow rate to carry all the incoming water and for avoiding that the top and bottom geotextiles get in touch, which would impair the capillary break. The performances of this innovative product has been evaluated through an extensive testing program, results of which are presented. Indications for specifications and installation are provided.
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