AIM:
To determine the soundness of cement by Le-Chatelier method as per IS: 4031 (Part 3) – 1988.
APPARATUS:
i) The apparatus for conducting the Le-Chatelier test should conform to IS: 5514 – 1969
ii) Balance, whose pemissible variation at a load of 1000g should be +1.0g
iii) Water bath
PROCEDURE:
- Place the mould on a glass sheet and fill it with the cement paste formed by gauging cement with 0.78 times the water required to give a paste of standard consistency (see Para 1.2).
- Cover the mould with another piece of glass sheet, place a small weight on this covering glass sheet and immediately submerge the whole assembly in water at a temperature of 27 ± 2oC and keep it there for 24hrs.
- Measure the distance separating the indicator points to the nearest 0.5mm (say d l ).
- Submerge the mould again in water at the temperature prescribed above. Bring the water to boiling point in 25 to 30 minutes and keep it boiling for 3hrs.
- Remove the mould from the water, allow it to cool and measure the distance between the indicator points (say d 2 ).
- (d 2 – d l) represents the expansion of cement.
RESULTS:
Calculate the mean of the two values to the nearest 0.5mm to represent the expansion of cement.
PRECAUTIONS:
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All the measurements should be done accurately.
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Do not apply extra pressure while filling the moulds.
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During boiling water level should not fall below the height of the mould.
TECHNICAL DISCUSSION:
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Volume expansion in cement mortar or in cement concrete is caused by the presence of unburnt lime (CaO), dead burnt MgO and also CaSO4.
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By Le-chatelier method we can only find out presence of unburnt lime (CaO).
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Presence of unburnt lime may develop cracks in the cement because of increase in volume.
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Free lime (CaO) and magnesia (MgO) are known to react with water very slowly and increase in volume considerably, which result in cracking, distortion and disintegration
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It will be better if you provide readings too
thank you for commenting here.. its not that easy to get the readings, for that i have to do the experiments again or i should go through my old lab manuals. i will definitely include observation and calculation etc.. as soon as possible.
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it would be much better if you post with drawing.
I have posted the drawing as featured image please have a look.