Tuesday, October 29, 2013

Le-Chatelier's Apparatus- Soundness Test of Cement

Hello,


  • Aim: To find out the Soundness of Cement.
  • Apparatus: Le- Ch-atelier's Apparatus, Weighing balance, measuring cylinder, trowel, mixing pans heater, thermometer.
  • Standard Reference:  Test is performed as per IS: 4031 (Part - 1) - 1988,
  • Theory: 
Cement of good quality does not contain the impurities like free lime, magnesia and sulphates, so this should be checked before use.

When it contains the impurities named above, it can expand after reacted with the water, which will result in the unwanted results like, cracking, unwanted expansion of the dimensions and lower strength. 
Le-Ch-atelier's Apparatus is the standard apparatus prescribed as per IS:5514 -1969 to check the presence of the impurities in cement.  Cement is said to be sound when the expansion is below 10 mm.


  • Procedure: 

Prepare a cement paste of 78% of standard consistency of the cement, and fill it into the split brass cylinder.

Cover the top and bottom of the cylinder and put it in water at 27 degrees Celsius for 24 hours.

After 24 hours, measure the separation between the two indicators at their pointed ends.

Then heat the whole water and immersed cylinder with paste up to a boiling temperature in 30-35 minutes and then boiling  for 3 hours.

After cooling it down, again measure the separation between the two pointers.

  • Calculations: 

Let the reading before putting the cement paste into the boiling temperature  = L1
                         After three hours of hot water immersion = L2
                  Expansion = L2-L1

  • Result: As the value of expansion is (Less/More)..... than 10 mm so the cement is .........(Sound/Unsound).

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Saturday, October 26, 2013

Tensile strength of Cement - Briquette Mould Test

Hi,

  • Briquette's mould machine is an apparatus which is used to form the briquettes of the cement mortar which are used to find out the tensile strength of the cement. 
These briquettes are of standard dimensions are constructed by pouring in the fresh cement mortar into the briquette mould and then followed by required curing.

  • After the curing, these mortar briquettes are tested for the amount of tensile load they can bear before getting failed. This load is the tensile strength of the cement. You have to test more than 3 briquettes, some suggest 6 nos. of them to get the desired results. Average of these results is taken as the final value.
Thanks!
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