Effect of Ultrasonic Energy and Multiwall Carbon-nanotube on the Shear Strength of Problematic Soils

Problematic soils are those that make the construction of foundations extremely difficult. Some problematic soils loss their strength, at saturated conditions. As silty soil and quicksands have low strength at saturated condition, it seems that stabilizing of these soils is necessary. In literature, stabilizing these soils by cement is more effective. On the other hand, by developments in nanotechnology within last three decades, researchers discovered a material with unique properties, named as carbon nanotube. The carbon nanotubes has very high strength even higher than steel, high elastic module and toughness and other unique properties. Within last three decades, many studies are concerned about applying this material in cement composites, but only we can find a few works related to use this material in soil stabilization. Since carbon nanotube attract each other, we should separate nanotube particles. In this study, different values of ultrasonic energy and polycarboxilate based super plasticizer solution was used to overcome carbon nanotubes agglomeration problem. As it is not possible to use carbon nanotubes in dry state, to investigating the effect of carbon nanotubes on the soils, the aqueous solution of carbon nanotube was added to the soil, using wet mix method. The samples were cured in water for 7 days. After performing direct shear test the shear strength and its parameters were evaluated.