a) A representative sample of mass of about 120 gm passing through 425 μ IS sieve is taken for the test. Mix the soil in an evaporating dish with distilled water to form a uniformpaste.
b) Adjust the cup of the device so that the fall of the cup on to the hard rubber bas is 10mm.
c) Transfer the portion of the paste to the cup of liquid limit device. Allow some time for the soil to have uniform distribution ofwater.
d) Level the soil topsoil so that the maximum depth of soil is 12 mm. A channel of 11 mm wide at the top, 2 mm at the bottom and 8 mm deep is cut by the grooving tool. The grooving tool is held normal to the cup and the groove is cut through the sample along the symmetrical axis of the top
e) The handle of the device is turned at a rate of about 2 revolutions per second and the number of blows necessary to close the groove along the bottom distance of 12 mm is counted. A sample of soil which closes the groove is collected.
f) The soil in the cup is re-mixed thoroughly (adding some more soil if required) some quantity of water which changes the consistency of soil, repeat the process. At least 4 tests should be conducted by adjusting the water contents of the soil in the cup in such a way that the number of blows required to close the groove may fall within the range of 5 to 40 blows. A plot of water content against the log of blows is made as shown in figure. The water content at 25 blows gives the liquid limit