Plastic Limit Test of Soil

A sample weighting about 15 grams is taken from the material passing the 425 micron sieve and is thoroughly mixed with water on a glass plate until it is plastic enough to be rolled into a ball. The ball of the soil is then rolled between the hand and the glass plate so as to form the soil mass into a thread. When the diameter of the thread becomes less than 3 mm, the soil is kneaded together and rolled out again. This process is continued until crumbling of the thread occurs at a diameter of 3 mm. The portions of the crumbled soil are gathered together and the moisture content of this soil determined.