experimentally investigation of nano clay effects on leaching and self-healing process of cracked clayey soils

Compacted clay layers are known as one of the common low impermeable layers used in geotechnical structures. due to geotechnical properties, these layers damaged through cracks in their lifespan. this research has attempted to improve the workability by using self-healing features of clays. by conducting numerous experimental tests, it has been shown that, by increasing the plasticity index of clays, the pace of crack healing process will be enhanced. experiments have shown that percentages of montmorillonite nano clay (mnc) are quite effective and reduce the flow rate in the samples, which is a sign of self-healing of the cracks by an nc additive. on this basis, nc can be perfectly used to repairing cracks in clayey soils. the results of this study show that in the sample with 1 mm crack, about 500 milliliters of water pass through the crack in 60 minutes under no pressuring conditions. while, if the sample contains 2 and 5 percent nc, the amount of water passing through the cracks within 60 minutes, will be 40 and 5 ml, respectively. this dramatic reduction for passing water reflects the positive effect of nano sized grains on the closure of the created cracks. therefore, it can be concluded that the self-healing process occurs earlier in smaller cracks, because the nc and soil particles can easily touch each other after swelling. five percent of mnc can insure the cracks closure at 100% density. in the samples with a density below 100%, there is a large gap between the soil particles, and the swelling of the nc from absorbed water dedicated to fill these voids.