Tests on soil

Plastic Limit of Soil

Code: This test is done as per IS: 2720 (Part 5) – 1985.

PREPARATION OF SAMPLE:

Take out 30g of air-dried soil from a thoroughly mixed sample of the soil passing through 425µm IS Sieve. Mix the soil with distilled water in an evaporating dish and leave the soil mass for naturing. This period may be upto 24hrs.

Procedure:

• i) Take about 8g of the soil and roll it with fingers on a glass plate. The rate of rolling should be between 80 to 90 strokes per minute to form a 3mm dia.
• ii) If the dia. of the threads can be reduced to less than 3mm, without any cracks appearing, it means that the water content is more than its plastic limit. Knead the soil to reduce the water content and roll it into a thread again.
• iii) Repeat the process of alternate rolling and kneading until the thread crumbles.
• iv) Collect and keep the pieces of crumbled soil thread in the container used to determine the moisture content.
• v) Repeat the process at least twice more with fresh samples of plastic soil each time.

Uses:

To determine the plastic limit of soil.