Determine Free Swell Index Of Soil

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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.

Free swell index = [Vd - Vk] / Vk x 100%
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


Degree of





















Very high




We are thankful to Er Jithesh for submitting the table to us

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  • Yogendra March 9, 2009 at 11:17 am

    with such notes, things becomes easy to learn

  • Rambha September 5, 2009 at 9:04 am

    Thanx a lot for making my search easier. Its a great help

  • Bijan March 12, 2010 at 5:51 pm

    Thanks alot

  • raj June 9, 2010 at 8:04 am

    What is the minimum limit of Free Swell as per I.S for filling purpose

    • suman kumar July 6, 2012 at 9:55 am

      first of all its not minimum but maximum limit & as per MORT&H specifications for roads and bridge work the maximum limit is 50 %(cl.305.2.1.2.). In any case this limit should not exceed for filling materials.

  • Motiul June 10, 2010 at 10:17 pm

    It was really helpful to me.Thnx a lot..

  • M K GUPTA December 3, 2010 at 11:38 am

    This is realy very useful for civil engineers

  • kaushik jadav December 24, 2010 at 10:48 pm

    what is the minimum limit of free sweel index and free sweell presser as per IS for back filling pourpoues.

  • tonya basar March 15, 2011 at 12:52 pm

    thanks its was very helpful

  • Nilesh Korde June 16, 2011 at 9:17 am

    Thanks for giving easy notes

  • Daramola sunday July 8, 2011 at 1:40 am

    Thanks for these easy and straight forward notes

  • Mokhtar Sayed July 8, 2011 at 5:30 pm

    Thanks alot for help

  • Manoj Chaudhary August 28, 2011 at 5:37 am

    A soil have liquid limit is 21 & plastic limit is 19. Pl. conferm me this soil is sutable for back filling?

  • madan s ambulgekar October 18, 2011 at 8:11 am

    pl. i want to know what will be the minimum F.S.I. of soil and will be the maximum F.S.I. of soil of any categaory.

  • Bharat Singh Rawat, Roorkee February 8, 2012 at 11:53 pm

    Excellent website.

  • SACHIN MANSINGH February 23, 2012 at 6:46 am

    thank you so much for your help.

  • Jayanthan July 26, 2012 at 2:29 pm

    what is the meaning of “Talus”?

  • Akshay kanade October 23, 2012 at 1:54 am

    Why free swell test is calculated

  • Meeran December 20, 2012 at 12:06 pm

    I want to know what is the limitation for free swell index…pls send me..

  • uwaoma b.u March 22, 2013 at 6:40 am

    is there difference between free swell and swell index

  • sameer singh November 7, 2013 at 5:25 am

    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

  • Post a comment

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