Object: To identify the soundness of a given cement by the le-chatelier method.
Standard Code: IS: 4031
What is the soundness of cement?
The ability of cement to retain its volume after it gets hardened is known as the 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 the soundness test of cement.
Required Material & Apparatus
- Le-Chateliermould
- Glass Sheets—2 Number
- Weight
- Trowel
- Mixing Pan
- Cement
Theory:
We know that cement is a macro product that consists of 8 micro-ingredients.
- Lime (60%-65%)
- Silica
- Aluminia
- Magnesia
- Iron oxide
- Calcium sulfate
- Sulfur Trioxide
- Alkaline
Each has its own set of properties and characteristics in order to make a perfect cement.
As lime is the main product, it contributes almost 70%.
A 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 the cement expands more after it gets hardened. The unsoundness of the cement makes
The work is saggy and looks like the below one. That’s the reason why we are testing the soundness of cement before using it. This test ensures that the cement will not go through any subsequent expansions due to the excess amount of lime present in it.
Procedure
- Before conducting the test, lightly oil the apparatus, such as Le-Chatelier mould, Glass, and glass plates (2)
- Take the required amount of cement, 200 g
- Prepare a cement paste by adding 0.78 times the water required for standard consistency. Mix the cement paste well using the trowel
- Now place the lightly oiled Le-Chatelier mold 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 top and put weight on it.
- Submerge the whole assembly into the water pot at room temperature and keep it undisturbed for 24 hours.
- Now remove the whole assembly from the water and measure the distance between the mould edges. Note that distance asL1. The measuring pointers should indicate to the nearest 0.5 mm.
- Submerge the mould again in the water, bring it to the boiling point, and cool it down to room temperature.
- Now again measure the mould edges distance asL2.
Calculation
Soundness of Cement = L1 – L2.
Conclusion
The value of soundness of cement obtained for Ordinary Portland Cement (OPC),
Low-heat cement, high-alumina cement, and rapid-hardening cement must not exceed 10 mm. Le Chatlier’s Method helps us to determine the lime present in the cement in excess. This is the excess lime that causes the expansion of cement.
Precautions
- The test is conducted with special care and guidance.
- Filling of moulds must not be done by applying extra pressure.
- During the process of boiling, the water level must not go below the height of the mould.
