17-01-2014, 02:59 PM
CALCIUM CARBIDE METHOD
AIM
To determine the water content in soil by calcium carbide
method as per IS: 2720 (Part II) - 1973.
PRINCIPLE
It is a method for rapid determination of water content from the
gas pressure developed by the reaction of calcium carbide with
the free water of the soil. From the calibrated scale of the
pressure gauge the percentage of water on total mass of wet soil
is obtained and the same is converted to water content on dry
mass of soil.
PROCEDURE
i) Set up the balance, place the sample in the pan till the
mark on the balance arm matches with the index mark.
ii) Check that the cup and the body are clean.
iii) Hold the body horizontally and gently deposit the levelled,
scoop-full of the absorbent (Calcium Carbide) inside the
chamber.
iv) Transfer the weighed soil from the pan to the cup.
v) Hold cup and chamber horizontally, bringing them together
without disturbing the sample and the absorbent.
vi) Clamp the cup tightly into place. If the sample is bulky,
reverse the above placement, that is, put the sample in the
chamber and the absorbent in the cup.