To obtain the liquid limit of a soil, a graph is plotted between:

Explanation:

The liquid limit of a soil is determined by plotting a graph between the water content and the number of blows required to close a standard groove cut in a soil sample in a liquid limit device.

This method is commonly known as the Casagrande method. During the test, the water content is varied, and the corresponding number of blows to close the groove is recorded. The graph typically shows a decreasing trend in the number of blows required as the water content increases.

The liquid limit is defined as the water content at which the groove closes at 25 blows.

Additional Informatio

Plastic Limit-

• Plastic Limit is the minimum water content at percent on dry bases at which soil enters from Semi-Solid State to Plastic State.

Shrinkage Limit-

• Shrinkage limit is defined as, the maximum water content at which a reduction in water content will not cause a decrease in the volume of a soil mass.
• It is the lowest water content at which soil can still be completely saturated.

Plasticity Index-

• The range of consistency within which a soil exhibits plastic properties is called the plastic range and is indicated by the plasticity index.
• The plasticity index is defined as, the numerical difference between the liquid limit and the plastic limit of soil: P.I = LL – PL.
• In the case of sandy soils, the plastic limit should be determined first. When the plastic limit cannot be determined, the plasticity index is reported as NP (non-plastic).
• When the plastic limit is equal to or greater than the liquid limit, the plasticity index is reported as zero.