To determine the liquid limit of fine soil by using CasagrandeApparatus.
When water is added to dry soil, it changes its state of consistency from hard to
soft. We can define liquid limit as the minimum water content at which the soil is still in
the liquid state, but has a small shearing strength against flow. From test point of view
we can define liquid limit as the minimum water content at which a pat of soil cut by a
groove of standard dimension will flow together for a distance of 12 mm (1/2 inch) under
an impact of 25 blows in the device
This test is done to determine liquid limit of soil as per IS: 2720(Part 5)-1985. After receiving the soil sample it is dried in air or in oven (maintained at a temperature of 600C). If clods are there in soil sample then it is broken with the help of wooden mallet. The soil passing 425 micron sieve is used in thistest.
Consistency of fine-grained soils may be defined as the relative ease with which a soil can be remoulded. Consistency limits may be categorized into three limits called Atterberglimits :-
1) Liquid limit
2) Plastic limit
3) Shrinkage limit
Liquid limit is the moisture content that defines where the soil changes from a plastic to a viscous fluid state. Other limits will be discussed during corresponding experiments.