Filter Paper Calibration Using Osmotic Coefficients to Measure Total Soil Suction: Fid-Bau Portal

Filter Paper Calibration Using Osmotic Coefficients to Measure Total Soil Suction

Pande, P. B. / Khandeshwar, S. R. / Bajad, S. P.

Suction is the pivotal parameter in arena of unsaturated soil. Filter paper method is the easy and cost-effective method for quantifying suction in which the calibration of filter paper is indispensable. The calibration curve with respect to total suction is impractical for measuring suctions a smaller than 1000 kPa. Thus, the distinct calibration curves are needed for measuring matric suction. Filter paper procedure is suitable up to the development of calibration curve in concern with total suction but difficult pertaining to development of matric suction calibration curve. Normally the pressure plate and pressure membrane were preferred for developing calibration curves, nevertheless these methods are having some limitations such as time consuming, skill and unavailability of equipment. The objective of this paper is to sidestep those limitations by adopting the prescribed procedure of establishing both curves required for measuring total as well as matric suction from filter paper technique. In this paper, the calibration equation for quantifying total suction was recognized from the wetting calibration curve achieved for Whatman No. 42 filter papers and matched with calibration equations developed by several other researchers. The total suction calibration equation was so selected that percentage error between obtained and selected must be less than 5%. Then, the drying calibration curve developed by the same researcher for the same filter paper was used for matric suction assessment of clayey soil used in this study. The procedure is recommended to reduce the efforts and additional time required for developing drying calibration curves. This technique can be appropriate in case of unavailability of equipment required for constructing drying calibration curve.