how to use Casagrande device step by step And what is the to

how to use Casagrande device step by step?

And what is the tools we should use? Like the device we used and the atm standards required while testing it. Like the 1/8 in slit and it cranks at 2 blows per second. Stuff like that

Solution

Casagrande appratus method is used to find Liquid limit is in the laboraroty .Casagrande appratus consists of brass cup which drops through a height of 1cm in a hard base when operated by the handle. this device is operated by turning the handle which raises the cup and let it drop on the rubber base. The height of drop is adjusted with helop of adjusting screws.

About 120g of air dried sample passing through 425 microns sieve taken in a dish and mixed with distilled water to form a uniform paste .A portion of this paste is placed in the top of liquid limit device and the surface is smoothened and a levelled with a spatula to maximum depth of 1 cm.A groove is cut through the sample along the symmetrical axis of the cup ,preferably one stroke.

Two types of tools are avilable A) Casagrande tool B)ASTM tool

Casagrande tools cuts a groove of width of 2mm at the bottom 13.6mm at the top and 10mm deep.The Casagrande tool is recommended for normal fine grained soil where as ASTM tool is recommened for sandy ,fine grained soil

After the soil pat has been cut by a proper grooving tool the handle is tuened at a rate of 2 revolutions per second until the two parts of the soil sample come into contact at the bottom of the groove along a distance of 12mm