A Round Robin Study for Benchmarking the Measurement of Soil Shrinkage Curve (SSC)

This study reports the findings from a round robin across 14 geotechnical engineering groups across several Australian and Indian universities, that was carried out to study the reproducibility and variability associated with the measurement of soil shrinkage curve (SSC). A standard operating procedure was developed for determining SSC of soils, that was provided to all the participating groups, along with two clay samples and shrinkage moulds. Variations were observed in the liquid limit and specific gravity of the two samples reported by the participating groups, that were sensitive to the testing method followed. A procedure was devised and applied to correct the SSCs reported by some of the groups, due to deviations from the expected soil behaviour. The suggested correction procedure addressed the uncertainties in the measurement of bulk volume and specific gravity of the samples. The mean and the median shrinkage limit obtained for both the samples, from the corrected SSCs, were close to each other. Barring a couple of exceptions, symmetric frequency distributions were observed for all the SSC fitting parameters (minimum void ratio, shrinkage limit, curvature of SSC) with the spread limited to a maximum of ± 2 times the standard deviation from the respective mean values.