|Experiment No. 5: Soil Atterberg Limits||
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Procedure for Liquid Limit
3. By holding a grooving tool perpendicular to the cup, carefully cut through the sample from back to front, and form a clean straight groove in the centre by dividing into two halves.
4. Turn the crank handle of the device at a steady rate of two revolutions per second. Continue turning until the two halves of the groove is closed along a distance of 13 mm. Record the number of blows to reach this condition.
5. Take about 15 gm of the soil from the joined portion of the groove to a moisture can for determining water content.
6. Transfer the remaining soil from the cup into the porcelain dish. Clean and dry the cup and the grooving tool.
Procedure for Plastic Limit
2. Take about 10 gm of the soil mass in the hand, form a ball, and roll it between the palm or the fingers and the glass plate using complete motion of the hand forward and reverse.
3. Apply only sufficient pressure to make a soil thread, and continue rolling until a thread of 3 mm diameter is formed. Comparison can be made with the metal rod.
4. If the diameter becomes less than 3 mm without cracking, turn the soil into a ball again, and re-roll. Repeat this remoulding and rolling process until the thread starts just crumbling at a diameter of 3 mm.
5. Gather the pieces of crumbled thread and place them in a moisture can for determining water content.