Cement – Irreplaceable material in any construction (as of now). It is essential to check its quality before using. we have already seen “how specific gravity of cement affects the strength?”
In this post, we are going to see another lab experiment which determines the soundness of cement.
Let’s get started
Soundness Test of Cement
What is soundness of cement?
The ability of cement to retain its volume after it gets hardened is known as Soundness of Cement. That means the cement should be at minimum volume change after it gets hardened.
The test conducted to identify the excess amount of lime in cement is known as soundness test of cement.
Significance – Why are we calculating this value for cement?
We know that cement is a macro product which consists of 8 micro-ingredients.
- Lime (60%-65%)
- Iron oxide
- Calcium sulfate
- Sulfur Trioxide
Each has its own set of properties and characteristics in order to make a perfect cement.
As you can see lime is the main product which contributes almost 70%.
Deficiency of lime makes the cement set quicker and affects the property of cement. Meanwhile, the excessive amount of lime makes the cement unsound. It means it cause the cement expands more after it gets hardened.
Unsoundness of cement makes the work saggy and looks like below one.
That’s the reason why we are testing the soundness of cement before using. This test ensures that the cement will not go any subsequent expansions due to excess amount of lime present in it.
How to calculate soundness of cement?
There are two methods available.
- Autoclave Method
- Le-chatelier Method
We are going to see Le-Chatelier method as per IS: 4031 (Part 3) – 1988. Find the complete IS Code List.
To identify the soundness of given cement by the le-chatelier method.
Required Material & Apparatus
- Le-Chatelier mould
- Glass Sheets – 2 Numbers
- Mixing Pan
- Before conducting the test lightly oil the apparatus such as Le-Chatelier mould, Glass plates(2)
- Take required amount of cement 200g.
- Prepare a cement paste by adding 0.78 times the water required for standard consistency. We will explain the 0.78 % cement consistency in upcoming Cement Consistency Test Post.
- Mix the cement paste well using the trowel.
- Now place the lightly oiled Le-Chatelier mould on the glass panel.
- Fill the mould with the prepared cement paste up to the top. While placing the cement hold the mould edges gently together.
- Now place another glass plate on the top and put weight on it.
- Submerge the whole assembly into the water pot at a room temperature and keep it undisturbed for 24 hours.
- Now remove the whole assembly from water and measure the distance between the mould edges. Note that distance as L1. The measuring pointers should indicate to the nearest 0.5 mm
- Submerge the mould again into the water and bring it to the boiling point and cool down it to room temperature.
- Now again measure the mould edges distance as L2.
Soundness of Cement = L1 – L2.
This value must not exceed 10 mm for Ordinary or OPC, Rapid, Low Heat, PPC and High alumina cement.
Experiment contents & Video Courtesy – LearnEngg.com
By the above method, we can find the excess amount of lime (unburned lime) which causes the volume expansion of cement.
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