Prediction of swelling characteristics of remoulded and compacted expansive soils using free swell index

Seasonal changes in moisture content result in volume change in expansive soils, which may damage structures founded on them. Evaluation of swelling characteristics of expansive soils, namely, swell potential and swelling pressure, is important for the design of foundations. Many relationships have been suggested for prediction of swell potential and swelling pressure from various index properties such as liquid limit, plasticity index, shrinkage index, activity, clay content, etc., and placement conditions such as initial dry unit weight, initial water content and initial surcharge pressure. Free swell index (FSI) indicates the potential expansiveness of a soil. FSI, being determined on the soil fraction <425 mum sieve like the other index properties of clays, is also an index property of an expansive soil. Hence, it can be used as a parameter in the relationships for swell potential and swelling pressure. This paper proposes relationships for predicting swell potential and swelling pressure of remoulded and compacted expansive soils using FSI and placement conditions. The relationships are based on experimental data for soil samples from 10 different sources.