Casagrande method in mechanical form is known as Liquid Limit Method and has been in use for soil mechanics for a number of years. The Liquid Limit data of soils is useful to correlate mechanical properties of soil, such as compressibility and lower shear strength. Liquid Limit is the water content at which soil passes from zero strength to an infinitesimal strength, hence the true value of liquid limit cannot be determined. For determination purpose liquid limit is that water content at which a part of soil, cut by a groove of standard dimensions, will flow together for a distance of 1. 25 cm under animpact of 25 blows in a standard liquid limit apparatus. The soil at the water content has some strength which is about 0. 17 n/cm. Sq. (17gms/sq. Cm. ) At this water content soil just passes from liquid state to plastic state.
Salient Features

• Specifications :It consists of a brass cup held on an adjustable bracket. The cup can be adjusted for a fall of 1 cm and can be raised and dropped on a rubber base of standard hardness by cam action. Complete with one casegrande grooving tool, one ASTM Grooving tool and a heigh gauge block (Type A of IS 9259)

Same as above but fitted with a motor geared down to give approximately 120 r.p.m. Suitable for operation on 230 volts, single phase, 50 cycles, A. C. Supply. 
Spares: casegrande grooving tool. ASTM grooving tool, height block, 1 cm high.

Same as above but fitted with a counter to register the number of blows.