Shear strenght improvement at the interface of lime-treated soil and concrete structures

Abstract

Lime stabilization can be used to increase the shaft resistance capacity of friction piles in clayey-soil. The concentration of the shear stress decreases gradually from the pile shaft outwards. By means of lime stabilization, the shear resistance can be increased in the zone close to the pile shaft where failure is most probable to occur. When the pile type is selected as cast-in-situ concrete pile, the free lime in fresh concrete may be considered to be the lime source for stabilization. However, the lime content in fresh concrete does not exceed one to two per cent. To provide extra lime, a slurry can be prepared in the bore-hole prior to concrete casting. Thus, the lime stabilization may occur through diffusion. In this study, direct shear tests were performed to observe the increase in shear strength at the interface of lime stabilized clayey-soil and concrete. By the lime stabilization of the clayey-soil, an increase of a great extent up to 100 per cent is observed in shear strength at the soil-concrete interface. The method proposed for increasing the shaft resistance capacity of cast-in-situ concrete piles by the lime stabilization is very easy and convenient for the field applications. Therefore, the necessary load carrying capacity of piles can be obtained economically without increasing the pile dimensions.|Keywords: Cast-in-situ concrete piles, skin friction, lime stabilization, diffusion.