Knead the soil for a few minutes to reduce its water content slightly. When the thread becomes a diameter of 1/8 in. Roll the test specimen between the palm or fingers on the ground glass plate to from a thread of uniform diameter.Ĭontinue rolling the thread until it reaches a uniform diameter of 3.2mm or 1/8 in. Limitations of Liquid Limit Test Procedure for Determination of the Plastic Limitįrom the 20g sample select a 1.5 to 2 g specimen for testing.
Whether water should be added or removed depends on the number of blows required to close the grove in the previous sample. Repeat steps 1 through 5 with a sample of soil at a slightly higher or lower water content. Remove a slice of soil and determine its water content, w.
Record the number of drops required to close the groove. The two halves must meet along a distance of 13mm (1/2 in).
Continue cranking until the two halves of the soil specimen meet each other at the bottom of the groove. Lift and drop the cup at a rate of 2 drops per second. When forming the groove, hold the tip of the grooving tool against the surface of the cup and keep the tool perpendicular to the surface of the cup. Keep the unused portion of the specimen in the storage container.įorm a groove in the soil by drawing the grooving tool, beveled edge forward, through the soil from the top of the cup to the bottom of the cup. Take care to eliminate air bubbles from the soil specimen. Place a portion of the prepared sample in the cup of the liquid limit device at the point where the cup rests on the base and spread it so that it is 10mm deep at its deepest point. See Also: Definition of Liquid Limit | Background of Liquid Limit Test. The liquid and plastic limits of soils are often referred the as the Atterberg limits. This test method covers the determination of the liquid limit, plastic limit and plasticity index of soils. The liquid limit, plastic limit and plasticity index of soils are also used extensively, either individually or together, with other soil properties to correlate with engineering behavior such as compressibility, permeability, compactibility, shrink‑swell and shear strength. This testing method is used as an integral part of several engineering classifications systems to characterize the fine‑grained fractions of soils and to specify the fine‑grained fraction of construction materials. Ground Glass Plate ‑ used for rolling plastic limit threads. Gage ‑ A metal gage block for adjusting the height of the drop of the cup to 10 mm. The device may be operated by either a hand crank or electric motor.Ĭup ‑ brass with mass (including cup hanger) of 185 to 215 g.Ĭam ‑ designed to raise the cup smoothly and continuously to its maximum height, over a distance of at least 180o of cam rotation, without developing an upward or downward velocity of the cup when the cam follower leaves the cam.įlat Grooving Tool ‑ a tool made of plastic or non‑corroding metal having specified dimensions. Liquid Limit Device ‑ a mechanical device consisting of a brass cup suspended from a carriage designed to control its drop onto a hard rubber base.