Geo-engineering properties of sedimented flyash deposit stabilized by lime pile

Abstract

In the present work, investigations were made to study the strength distribution of sedimented flyash deposit surrounded by lime column over a stabilization period of 90 days. Flyash slurry was prepared and allowed to fall from a constant height of 1 m in a test tank having 1m diameter and 1.2 m height. Prior to saturation, a single lime column of 0.1 m diameter over full length of deposited slurry was installed in the test tank after the initial sedimentation period of 30 days. It is reasonable to assume that the lime will flow easily downward into flyash deposit in vertical direction and the strength may also increase with the availability of lime. To obtain variation of strength in vertical direction, lime column of 0.2 m height was made in other tank in a similar manner. A series of uniaxial strength and direct shear tests were performed on the samples extracted at various depths and radial distances. It was observed that the lime column inclusion enhance the strength of sedimented flyash deposit with stabilization time. Also significant improvement in strength was observed up to a horizontal distance of 3 D (where D is the diameter of lime column) from the center of column and vertical distance of 4 D from bottom of lime column. A comparative study showed that the strength of stabilized mass is much higher than the un-stabilized one. The method has also proved to be useful in reducing the contamination potential of the ash leachates, thus mitigating the adverse environmental effects of ash deposits.