Saturated soil samples are placed in contact with a saturated porous membrane resting on a screen disk installed within a high-pressure chamber. The bottom of the membrane-screen assembly is maintained at a atmospheric pressure by means of a small drain tube or opening through the bottom of the pressure chamber. A desired air pressure admitted to the pressure chamber and consequently to the top of the membrane, creates a pressure drop across the membrane. The saturated soil samples on the membrane establish equilibrium with the water in the membrane. The water, held at a tension less than the pressure drop across the membrane, will then move out of the soil, through the membrane, and out through the drain hose. When water has ceased to flow from the sample and the membrane, indicating equilibrium for that particular tension, the moisture content of each sample is determined. A series of these tests at various tensions is required to prepare a complete curve of the capillary-moisture properties for any particular soil.
5 or more
Material passing #10 sieve of approximately 25 g, either undisturbed or compacted into a 2 in diameter x 1 in test specimen cutter
Capillary-moisture, fine textured soils, pressure-membrane