Geocomposite capillary barriers to reduce frost heave in soils

We investigated the potential for geosynthetic capillary barriers to reduce frost heave in soils by freezing upright, cylindrical soil specimens with horizontal disks of geosynthetics placed in them. During freezing, water wa s freely available at 25 mm above the base of 150 mm high specimens. The ge osynthetics were located 5 mm above the water supply. We measured frost hea ve and final water content profiles of specimens containing geosynthetic ca pillary barriers and control specimens. The thermal conditions of the tests were typical of pavements in cold regions. Geotextiles prepared to simulat e field conditions (i.e., moistened and containing soil fines) failed to si gnificantly reduce frost heave. However, geocomposites comprising needle-pu nched polypropylene geotextiles sandwiching a drainage net, prepared in the same way as the moistened geotextiles containing soil fines, reduced frost heave when the soil water suction head in the overlying soil was 1800 mm o r more. The geocomposites did not significantly reduce heave when the soil water suction head in the overlying soil was 800 mm or less. This is probab ly due to water migration between the two layers of soil, through the geote xtiles and along the net of the geocomposite.