LIQUID LIMIT
1. INTRODUCTION
Liquid limit is significant to know the stress history and general properties of the soil met
with construction. From the results of liquid limit the compression index may be estimated.
The compression index value will help us in settlement analysis. If the natural moisture content
of soil is closer to liquid limit, the soil can be considered as soft if the moisture content is lesser
than liquids limit, the soil can be considered as soft if the moisture content is lesser than liquid
limit. The soil is brittle and stiffer.
2. THEORY
The liquid limit is the moisture content at which the groove, formed by a standard tool into
the sample of soil taken in the standard cup, closes for 10 mm on being given 25 blows in
a standard manner. This is the limiting moisture content at which the cohesive soil passes
from liquid state to plastic state.
3. PROCEDURE
1. Soil with 200g that passes through the sieve size of 0.435 mm is taken. The soil is put in the
ceramic cup and water is added to mix thoroughly with a spatula.
2. The wet soil is putted into the testing cup and no air trap in the soil is ensured. The soil with
the top surface of the test cup is leveled using the spatula.
3. The test cup that contains the sample is put on the floor.
4. The come is lowered until the tip just touches the surface of the sample.
5. The dial gauge is set to zero.
6. The cone is released by pressing the release button for 5 seconds. After 5 seconds, the release
button for locking the cone is let go so as not to allow the cone to carry on penetrating into the
sample.
7. the reading on the dial gauge is recorded. The reading shows the depth of penetration in 5
seconds.
8. A little of the sample is taken for obtaining the moisture contents.
9. The procedure is repeated for 2 times.
10. The procedure as above is repeated for five moisture contents.
11. Graph of Moisture Content (linear scale) versus the Cone Penetration (logarithmic scale)
is plotted. the moisture content for the cone penetration of 20 mm is obtain form the graph.
This moisture content is the liquid limit of the sample.
FLOWCHART
1. Take 200 g of soil that passes through the sieve size of 0.425 mm. Put the soil in the
ceramic cup and add water and mix thoroughly with the spatula.
2. . Put the wet soul into the testing cup (55 mm x 40 mm) and make sure that there is no
air trap in the soil. Level the soil with the top surface of test cup using the spatula.
3. Put the test cup that contains the sample on the floor of the test apparatus and lower the
cone until the tip just touches the surface of the sample. Then, set the dial gauge to zero.
4. Release the cone by pressing the release button for 5 seconds. After 5 seconds, let go
the release button for locking the cone so as not to allow the cone to carry and record
the reading on the dial gauge.
5. Take a little of the sample for obtaining the moisture contents then repeat for 2 times.
Repeat the procedure as above for at least five moisture contents.
6. Plot the graph of Moisture Content versus the Cone Penetration. From the graph,
obtain the moisture content for the cone penetration of 20 mm. This moisture content
is the liquid limit of the sample.