To determine the free swell index of soil as per IS: 2720 (Part XL) – 1977. Free swell or differential free swell, also termed as free swell index, is the increase in volume of soil without any external constraint when subjected to submergence in water. The apparatus used :
i) IS Sieve of size 425µm
ii) Oven
iii) Balance, with an accuracy of 0.01g
iv) Graduated glass cylinder- 2 nos., each of 100ml capacity
strong>Procedure to determine Free Swell Index Of Soil
i) Take two specimens of 10g each of pulverised soil passing through 425µm IS Sieve and oven-dry.
ii) Pour each soil specimen into a graduated glass cylinder of 100ml capacity.
iii) Pour distilled water in one and kerosene oil in the other cylinder upto 100ml mark.
iv) Remove entrapped air by gently shaking or stirring with a glass rod.
v) Allow the suspension to attain the state of equilibrium (for not less than 24hours).
vi) Final volume of soil in each of the cylinder should be read out.
REPORTING OF RESULTS
Free swell index = [Vd – Vk] / Vk x 100%
where,
Vd = volume of soil specimen read from the graduated cylinder containing distilled water.
Vk = volume of soil specimen read from the graduated cylinder containing kerosene.
|
Free Swell Index |
Degree of expansiveness |
LL |
PL |
SL |
|
<20
|
Low
|
0.50
|
0-35%
|
>17%
|
|
20-35
|
Moderate
|
40-60% |
25-50% |
8-18% |
|
35-50 |
High |
50-75% |
35-65% |
6-12%
|
|
>50 |
Very high |
>60% |
>45% |
<10% |
We are thankful to Er Jithesh for submitting the table to us
If you have a query, you can ask a question here.
what value should be suitable for using soil at different places such as for subgrade,for foundation…according to IS codes.ans what is significance of this test
Very useful
I’ve seen the material given. Thankyou so much.
However, I have a question and leave a comment.
What is the ‘LL, PL, SL’ on the right side of the table?
Please reply me. Thanks~
Sir
Please tell me those situations when soil volume increase in kerosin and remain constant in water.Is it possible ?
Let me know about in detail.
Thanks and regards.
J.C.Sharma
Sir, Good day. Gods grace I got this link. I have a bore piling project in which the properties of bentonite is given ” The differential free swell shall be more than 540 percent”. In your post above it is felt that the this value is very high. Will this high value will come for bentonite? Please advice.
SL full form
Why kerosene oil is use in this test and which other oil we can used instead of kerosene oil
What to use in place of kerosene oil, if it is not available.