Effects of Freezing on the Microstructure of Geotextiles
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Published:1990
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Examination with a scanning electron microscope (SEM) revealed that a single freeze-thaw cycle in distilled water did not damage the fibers of a needle-punched or a heat-bonded geotextile; however, significant soil particle contamination occurred in the needle-punched fabric after being frozen in soil in laboratory tests. (The heat-bonded fabric was not tested in this manner.) The presence of soil particles both in fabric pores and on fabric fibers suggests that the fabric's ability to reduce frost heave is degraded. Laboratory frost heaving tests showed that a fabric's ability to mitigate frost heave decreased after having been exposed to vertical water flow in soil prior to freezing. The flow is thought to have introduced soil fines into the fabric, but this idea was not confirmed by inspection before freezing. A pumping test conducted with soil in a triaxial cell, designed to simulate stresses on a pavement subgrade during thawing, did not noticeably contaminate the needle-punched fabric tested. Furthermore, fabrics subjected to the triaxial cell pumping performed as well as new fabrics in mitigating frost heave in laboratory soil freezing tests. Whether the triaxial cell pumping test and/or the vertical water flow procedures simulate field conditions has yet to be determined.