Comparison of Chilled-mirror Measurements and Filter Paper Estimates of Total Soil Suction

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Published in: ASTM Geotechnical Testing Journal, Vol. 30, No. 5, 2007.


A comparison of chilled-mirror total suction measurements with those estimated from filter paper total suction data show general agreement. However, there are significant discrepancies that are similar to those previously reported by others. The nature and magnitude of the discrepancies are consistent with: (a) possible errors in chilled-mirror total suction measurements due to incomplete equilibration in the sealed test chamber of the chilled-mirror device, and (b) possible errors in estimated filter paper total suction values due to natural variations of the zero-water-content intercept in the log total suction versus water content relationship. The possible errors in chilled-mirror measurements are easily avoided. The possible errors in estimated filter paper measurements can only be minimized by avoiding the need for an assumed zero-water-content intercept. This can be accomplished far more easily with the chilled-mirror device than with the filter paper method.