An Alternative Medium for the Measurement of Soil Suction by the Filter Paper Method

Soil suction is the negative pressure within soil particles, which is a function of the moisture content. It plays an important role in agriculture, civil engineering, and geology. Suction is used in practice to identify expansive soils, to locate heave areas, to develop moisture requirements for arid land plants, to measure for collapse of soils around a footing, and to monitor flow movement of moisture. Soil suction varies with moisture content, and the relationship between suction and water content is known as the soil-moisture characteristic curve of a soil. There are several laboratory tests available to measure suction, but the filter paper test is an easy and inexpensive method that provides the widest range of suction values. The filter paper test is an indirect method of measuring suction, and uses the filter papers as indicators. The calibration curves developed for the filter papers are steep sloped and the accuracy of the test requires the mass to be measured to 0.0001 grams. An investigation of a new medium to provide a higher resolution and shorten the period of equilibrium was done using polymer strips found in household products. The resolution of the test was improved using the polymer strips but the time for equilibrium was not shortened. The polymer strips and filter papers were compared using similar soil samples. The polymer and the filter paper results were similar. The polymer strips improved the resolution and had repeatable data.