DISPERSIVE CLAY STABILISED BY ALUM AND LIME
Keywords:Dispersive Clay, Alum, Lime, Unconfined Compression Test, Direct Shear Test
Dispersion phenomenon can cause erosion problems during hydraulic construction projects such as earth dams, channels, hydraulic installations and embankments. However, aluminum sulfate can be used to stabilize dispersive clay. Tests were done to consider the effects of alum and lime additions on shear strength parameters of clay as secondary effects. Clay for samples was taken from the Mirzakhanluo Dam, located in Tarom County, northwestern Zanjan Province of Iran. In this research, the clay sample was subjected
to direct shear testing; the clay was tested with optimum moisture under varying percentages of alum (0, 0.3, 0.6, 1, 3, and 5 as percentage of dry soil weight) for 28 days. Also, unconfined tests were conducted on samples with equal amounts of moisture, alum and lime under the different treatment durations of 7, 14, and 21 and 28 days, separately. Results for the direct shear test indicated that the maximum cohesion was recorded in the sample with 1% alum. Results also showed that the internal friction angle decreased in samples with alum percentage up to the level of 0.6% and at levels higher than that it showed an increase. Generally, results
showed that soil shear strength was higher in soil stabilized by alum than in unstabilized soil. Results of the uniaxial test, determined that alum and lime additions to dispersive soil and its treatment, compression strength was not limited and elastic modulus showed an increase. The highest evaluations were determined for amounts of elastic modulus and uniaxial strength in soil with 3% lime or 5% alum on the 28th day of treatment.