To determine the soundness of cement by Le-Chatelier method as per IS: 4031 (Part 3) – 1988.
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
- 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.
Calculate the mean of the two values to the nearest 0.5mm to represent the expansion of cement.
All the measurements should be done accurately.
Do not apply extra pressure while filling the moulds.
During boiling water level should not fall below the height of the mould.
Volume expansion in cement mortar or in cement concrete is caused by the presence of unburnt lime (CaO), dead burnt MgO and also CaSO4.
By Le-chatelier method we can only find out presence of unburnt lime (CaO).
Presence of unburnt lime may develop cracks in the cement because of increase in volume.
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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