Behavior of stabilized soil cushions under cyclic wetting and drying

The use of cushion below the base of foundation resting on expansive soil is very attractive from the view point of economy and overcoming the problems associated with construction of structures over expansive soil. Extensive studies on cohesive non-swelling soil (CNS) as a cushion show that it is not always effective with cycles of wetting and drying. With increase in the number of cycles, the CNS material has been shown to become less and less effective with time. Also, it is very rare to get CNS material in the nature. The present paper describes the possibility of using stabilized soil as a cushion material. The soil used as cushion in this investigation is not CNS, but its properties shows that it can be considered as a cohesive non-swelling soil. It has been observed that the soil cushion stabilized with lime and cement shows a substantial performance improvement in all the wetting and drying cycles and also in the key parameters i.e. highest swollen level, lowest shrunken level, equilibrium swollen and shrunken level, equilibrium band width, operating displacement, extreme displacement and operating middle level. Lime stabilized soil cushion is more effective than cement stabilized soil cushion.