Effect of freeze-thaw cycles on characteristics of marl soils treated by electroosmosis application

Abstract

Marly clay consists of 35 to 65% calcareous materials and it has a very low load bearing capacity, particularly after experiencing the freeze-thaw cycles. Since the presence of this soil may cause erosion and the probable succeeding destruction of foundations and embankments, and occurrence of tensile cracks in roads, the treatment of marl is desirable in construction. In this study, initial tests revealed that the Unconfined Compressive Strength (UCS) of a highly calcareous marl was dramatically decreased to almost zero only after the first freeze-thaw cycle. Afterwards, the marl samples were treated by electroosmosis application in an electroosmosis cell designed for this study. The effects of various voltage gradients of 0.46, 0.92 and 1.84 V/cm and the treatment periods of 1, 3 and 7 days on characteristics of marl were investigated experimentally. After the electroosmosis treatment, undisturbed samples were taken from the zones around anode, cathode and in-between of the poles. The UCS of the samples was measured after applying up to 16 freeze-thaw cycles. The results indicated that the electroosmosis treatment increased the load bearing capacity of the marl significantly. The UCS of a sample taken from around the anode increased by 2.8 times in comparison with the untreated one. As the best case, a seven-day application of electroosmosis under the voltage gradient of 0.92 V/cm showed a UCS value of about 271 kPa even after 16 freeze-thaw cycles.