EXPERIMENTAL STUDY ON BEHAVIORAL PARAMETERS OF EXPANSIVE SOIL TREATED WITH SALT WATER

Abstract

Expansion and shrinkage are common features in the expansive soil because of the presence of clay minerals or chemically evoked changes. Chemical stabilization has been proved to be effective alternative solution to overcome the undesirable swelling behavior. This research highlights the effect of adding sodium chloride salts to expansive soil in improving swelling characteristics and change in soil index properties. An experimental program developed to investigate the effect of salt water on the engineering properties of high swelling clays. The laboratory tests were carried out in the soil mechanics laboratory of Al Azhar University. The materials used in this research were silty clay obtained from Bait El Watan project in New Cairo city and saline water at various NaCl concentrations of (5, 10,20,30,50 and 60%). A series of laboratory tests were carried out. Based on the obtained results, A concentration of 20% NaCl showed optimum improvement in swelling properties. To simulate field conditions, an experimental model was constructed to evaluate the effect of salt water with optimum concentration on expansive soil. However, the results showed that swelling properties of soil were optimized at 20%Nacl concentration. Swelling heave readings as recorded from large scale experimental model testing improved from 1.525mm to 1.355mm for original and treated soil, with a reduction of 11%. It is also observed that swelling heave values measured for the treated soil sample when re-immersed in fresh water increased by 145% at the top of soil.