SUBGRADE STRENGTHENING OF ROADS ON BLACK COTTON SOIL USING QUARRY DUST

Abstract

Black cotton soil is a highly clayey soil it has very low bearing capacity and high shrinkage and swelling characteristics. Due to its peculiar characteristics, it forms a very poor foundation material for road construction and due to very low CBR values of black cotton soil; excessive pavement thickness is required for designing flexible pavement. Ground improvement technique such as soil stabilization and reinforcement are employed to improve the mechanical behavior of soil thereby enhancing the reliability of construction. The wide spread of black cotton soil in various places in India posses problems to the construction activities, especially sub grade problems. The quarry dust a by-product from the crushing process during quarrying activities is one of the waste products. This by product is left in the neighborhood of the quarry causing environmental pollution and serious health hazards. Quarry dust consists mainly of excess fines and it exhibits high shear strength which is highly beneficial for its use as a geotechnical material. Hence an experimental study is undertaken to check the suitability of quarry dust as a stabilizer to improve the engineering properties of black cotton soil. Black cotton soil sample which is used for the study is taken from an area called Bhimavaram which is located in East Godavari district of Andhra Pradesh state in India. The quarry dust sample which is used in improving the black cotton soil characteristics is taken from Tekkali Srikakulam district located in Andhra Pradesh state, India. An attempt is being done to stabilize the black cotton soil by adding quarry dust in percentages of 10%, 20%, 30%, 40%. The test values of CBR test, swell test are compared for different percentages of quarry dust with black cotton soil values