Shrink-swell index database for Melbourne

Jie Li, Jian Zou, Peter Bayetto and Nick Barker

Abstract

A series of laboratory tests have been performed, including shrink-swell, liquid limit, plastic limit, linear shrinkage and soil suction on soil samples collected from 47 different field sites across 37 suburbs of Melbourne. The sites cover a wide range of soils and different geological conditions and geographical settings. The results of the laboratory tests were used to establish a database of tested shrink-swell index (Iss) values. An interactive map showing the distribution and reactivity of Melbourne soils has been developed that can be used in routine practice by local engineers to assess and calibrate the shrinkage indices estimated on a visual-tactile basis. The study indicates that there is a significant variation in Iss results across any particular soil type and that a blanket estimated value based on that soil type may not be entirely appropriate. Highly reactive soils are mainly present in the western and northern suburbs of Melbourne, and many of these areas have a shrink-swell index higher than 6% strain /pF. Correlations of shrink-swell index, liquid limit, plastic limit, plasticity index and linear shrinkage have also been attempted and the results show that simple index tests are not a reliable substitute for Iss testing.