Redesigned Filter Paper Method: Protocol and Assessment Using Reconstituted Samples

• Published in: Geotechnical testing journal 2021-03, Vol.44 (2), p.237-254
• Main Authors: Walshire, Lucas, Berry, Woodman, Taylor, Oliver-Denzil
• Format: Article
• Language: English
• ISSN: 0149-6115; 1945-7545
• DOI: 10.1520/GTJ20190420

The soil-water retention curve defines a relationship between the water content of a soil and the corresponding pressure at which the soil-water-air is in equilibrium. In cases in which undisturbed sampling are not feasible, especially for nonplastic and low-plastic soil fabrics, reconstituted soil samples are required. A newly designed mold was devised for use with reconstituted soil samples and the filter paper test. The newly designed mold consisted of a #200 wire mesh that allows for three-dimensional vapor flow. Implementing this new apparatus in conjunction with an energy-based reconstitution protocol minimizes inconsistencies across the test specimen such that variabilities associated with the filter paper testing method can be isolated and calibration curves verified. Calibration procedures are assessed and results are presented based on axis translation and verified by tensiometer measurements. This redesigned filter paper test was then conducted over a range of nonplastic to low-plastic soils yielding comparable results with published field studies and data bases. It can be concluded from this investigation that the filter paper method, using an energy-based reconstitution method and a mesh mold, is comparable to non-filter paper testing methods and is preferable for some applications because of its simplicity and relative short testing times.