Sulphate attack and ettringite formation in the lime and cement stabilized marine clays

Swelling and shrinkage behaviour of marine clays impose foundation problems that may sometimes results in excessive settlements. Improving the behaviour of soft clays using lime or cement is not new. Recent studies reported the occurrence of high swelling and pavement failures in lime and cement stabilized clays containing sulphates. The above phenomena resulted in the formation of swelling minerals such as ettringite and thaumasite. In this paper, the earlier reported case histories of sulphate attack in lime and cement stabilized clays have been reviewed, and a list of precautionary measures to be adopted for controlling the ettringite formation have been suggested. An attempt has been made to investigate the application of deep lime mixing technique in sulphate enriched marine clays. Physico-chemical and engineering properties of the lime treated clays containing ettringite have been examined. Test results indicate that lime and cement stabilization techniques should be cautiously approached in sulphate enriched clays.