For assessment of the liquid limit of soil sample

Theory

The liquid limit of a soil refers to the water proportion at which the soil performs virtually like a liquid, however has minor shear strength. It flows to adjacent the groove in mere 25 blows in Casagrande’s liquid limit equipment.

Since, it is hard to get precisely 25 blows in a test, 3 to 4 tests are carried out and the number of blows (N) mandatory in each test is assessed. A semi-log plot is then illustrated among log N and the water proportion (w). The liquid limit refers to the water proportion conforming to N=25, as acquired from the plot.

Equipment

• Casagrande’s liquid limit device
• Grooving tolls of both standard and ASTM types
• Evaporating dish or glass sheet
• Spatula
• 425   IS sieve
• Weighing balance accuracy 0.01g.
• Oven
• Spatula
• Wash bottle

Process

1. Conform the drop of the measure of as far as possible gadget by discharging the two screws at the top and by utilizing the handle of the grooving device or a gage. The drop ought to be precisely 1cm at the purpose of contact on the base. Fix the screw after change.

2. Take around 120g of the air-dried soil test passing 425 IS sifter.

3. Blend the specimen altogether with refined water in a dissipating dish or a glass plate to frame a uniform glue. Blending ought to be proceeded for around 15 to 30 min, till a uniform blend is acquired.

4. Hold the blend under damp conditions for acquiring uniform dampness dissemination for adequate period. For some fat clays. This developing time might be up to 24 hours.

5. Take a part of the developed glue and remix it completely. Put it in the measure of the instrument by a spatula and level it by a spatula or a straight edge to have a base profundity of the soil as 1cm at the purpose of the greatest thickness. The overabundance soil, if any ought to be exchanged to the evaporating dish.

6. Cut a groove in the sample in the container by utilizing the fitting device. Draw the scoring device through the glue in the glass along the symmetrical pivot, along the breadth through the inside line of the container. Hold the instrument opposite to the glass.

7. Turn the handle of the gadget at a rate of 2 cycles for every second. Check the quantity of blows until the two parts of the soil sample come in contact at the base of the notch along a separation of 12mm because of stream and not by sliding.

8. Gather a delegate test of the dirt by moving spatula width-wise from one edge to the next edge of the dirt cake at right edges to the groove. This ought to incorporate the bit of the groove in which the dirt streamed to close the notch.

9. Expel the rest of the soil from the container. Blend it with the dirt left in the evaporating dish.

10. Change the water content of the blend in the evaporating dish either by including more water if the water substance is to be expanded or by manipulating the soil, if the water substance is to be diminished. For no situation the dry soil ought to be added to lessen the water content.

11. Rehash the means 4 to 10 and decide the quantity of blows (N) and the water content for each situation.

12. Draw the stream bend between log N and w, and decide as far as possible comparing to N=25.

Data Sheet for Liquid Limit Test

Sl. No.	Observations and Calculations	Determination No.
		1	2	3
Observation
1	Number of blows (N)
2	Water content can No.
3	Mass of empty can ( )
4	Mass of can + wet soil ( )
5	Mass of can + dry soil ( )
Calculations
6	Mass of water =
7	Mass of dry  soil =
8	Water content = w = [(6) / (7)] x 100

 

Outcome

Draw a flow curve between log N and w.

Liquid limit (for N=25) =

 

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