The shrink swell test of determining Expansive Site Soil Classes is Fatally Flawed

Presented by Nick Rogers, Tonkin & Taylor

The shrink swell test, which combines both the shrink strain and the swell strain, was developed in Australia in the 1980s. This test now underpins a codified approach to the foundation design of lightweight buildings on expansive (reactive) soils in Australia and New Zealand.

This presentation sets out the results of a critical examination of datasets of shrink swell tests undertaken in Auckland, New Zealand and Victoria, Australia and concludes that in these datasets the shrink swell test has a significant shrink strain bias which makes it unreliable as the sole basis for foundation design guidance on expansive soils