DETERMINATION OF WATER CONTENT OF SOIL SOLIDS BY OVEN DRYING
METHOD ( IS 2720 (part II)-1973)
Aim: To determine the water content of soil solids by Oven Drying method.
Equipments Required:
a) Non-corrodible airtight containers.
b) Balance weighting to accuracy of 0.04% of the weight of the soil taken for test.
c) Desiccators with suitable desiccating agent.
d) Thermostatically controlled oven to maintain temperature 110⁰C±5⁰C.
e) Other accessories.
Theory:
In almost all soil tests natural moisture content of the soil is to be determined. The knowledge of
the natural moisture content is essential in all studies of soil mechanics. To sight a few, natural
moisture content is used in determining the bearing capacity and settlement. The natural moisture
content will give an idea of the state of soil in the field. Water content, w of a soil mass is
defined as the ratio of mass of water in the voids to the mass of solids:
w=(W2-W3)/(W3-W1)x100 %
Where, W1= Weight of empty container in grams
W2 = Weight of container + wet soil in grams
W3 = Weight of container + dry soil in grams
Procedure:
a) Clean the container with lid and find the mass (W1 in g).
b) Select the required quantity of moist soil sample, place it in the container, place the lid on it,
and weigh it (W2 in g).
c) Keep the container in the oven with lid removed and dry it for at least 24 hr. at a temperature
of 110⁰C till the mass remains constant. d) Remove the container from the oven, replace the lid,
and cool it in desiccators. Find the mass (W3 in g).
e) Determine the water constant w by using the above equation.
f) Repeat the experiment with other test samples.
Table:
Sl No Particulars Test No:1 Test No:2 Test No:3
(w1) (w2) (w3)
1 Weight of empty container (W1), g
2 Weight of container + wet soil (W2),
g
3 Weight of container + dry soil (W3),
g
4 Water content, w
5 Average water content, w = (w1+
w2 + w3)/3
Calculations:
w= (W2-W3)/(W3-W1)x100 %
Result:
Average=
Conclusion:
The experiment is conducted as per the IS code procedure. The water content of the soil
sample is determined. Water content, w = _____%. The value is verified and the three
phase system is sketched
Precautions:
1) Ensure that soil samples are between 350 to 400g. Larger samples take too long to dry,
while smaller samples lead to inaccurate results.
2) Ensure that the oven temperature is maintained at 110⁰ C ± 5 ⁰C. Do not allow the oven
door to stay open for too long, as it takes a while for the oven to regain the drying
temperature.
3) Do not put moist samples in the oven on a shelf below dry samples. Moist samples
should be placed on the top shelf and all partially dried samples placed on the lower
shelf.
4) Do not over-load the oven, as this will create a much longer drying time.
5) Do not allow dried samples to pick up moisture after they are removed from the oven.
Weigh them immediately after drying.
6) Soils and aggregates may contain bacteria and/or organisms which can be harmful for
one's health. Wearing dust masks and protective gloves when handling materials is
advised. The use of heat resistant gloves/mitts or pot holders to remove samples from the
ovens is recommended.
7) Prior to handling oven, testing or disposing of any waste materials, students are required
to read do’s and don’ts of the Geotechnical engineering laboratory.
