Hello and welcome to this video on how to measure the free swell index of soil. The free swell index is a parameter that helps to identify the soil’s potential to swell under different field conditions. Swelling soils can cause problems for foundations and structures, so it is important to test them before construction.
In this video, we will show you how to perform a simple test for measuring the free swell index of soil using some basic apparatus. You will need:
A 425-micron IS Sieve
Two glass graduated cylinders of 100 ml capacity
Kerosene oil
Distilled water
A glass rod
A weighing balance
An oven
The procedure is as follows:
Step 1: Take two oven dry soil specimens of 10 g each that pass through 425-micron IS Sieve. You can use a weighing balance to measure the mass of the soil specimens. Note that for highly swelling soils, such as sodium bentonites, you may need to use a smaller sample size of 5 g or a larger cylinder of 250 ml capacity.
Step 2: Pour each soil specimen in each of the two glass graduated cylinders of 100 ml capacity. Fill one cylinder with kerosene oil and the other with distilled water up to the 100 ml mark. Kerosene oil is a non-polar liquid that does not cause swelling of the soil, so it will give us the original volume of the soil samples.
Step 3: After pouring the liquids, remove any entrapped air bubbles by gently shaking or stirring with a glass rod. Then let the soils in both cylinders settle down for at least 24 hours until they reach an equilibrium state of volume without any further change.
Step 4: After 24 hours, read out the final volume of soils in each cylinder. The level of the soil in kerosene cylinder is the original volume (Vk) and the level of soil in distilled water cylinder is free swell level (Vd).
Step 5: To calculate free swell index, use this formula:
Free swell index (%) = (Vd - Vk) x ,o() / Vk
where Vd is volume of soil specimen in distilled water and Vk is volume of soil specimen in kerosene.
The higher the free swell index, the more swelling potential the soil has.
That’s it! You have successfully measured free swell index using this simple test. We hope you enjoyed this video and learned something new. Thanks for watching and see you next time!"
18 мар 2023
