Soundness Test of Cement

Support civil June 17, 2018 Building material , Video 1 comment

It is important that no change in the volume of cement take place after it's harding as it significantly affects the durability of the structure in which it is used for the construction .
Unsoundness of cement is due to the presence of lime ,magnesia and sulphur.

Unsoundness due to lime
Unsoundness due to lime is determine using Lechatelier's test which consist of a split cylinder of diameter and height 50mm and indicator the arms of length 165mm .Which are place on either side of split .
In order to perform this test 100 grams of the cement iis guaged with .78P (78% of the water required to prepared cement paste of standard consistency is added ) and the paste form is filled the split cylinder and covered from top and bottom with the help of glass plates .
The entire assembly is then immersed in water having the temperature 27 to 30 degree celsius
for 24 hours .
The assembly is removed and distance between the indicator arms is noted .(x)
The assembly is again immersed in the water temperature of which is increased upto its boiling point within 25 to 30 minutes and it maintain for next 5 hours.
The assembly is removed from the water allow to cool off and distance between the indicator arms is again noted (y).
For OPC the difference between the two reading should not exceed 12mm.

credit Civil Engineering Test

Unsoundness Due To Magnesia
Unsoundness due to magnesia is determined using autoclave test which is sensitive to both volume changes due to lime and magnesia.
In this test a block of 25x25x282 mm is prepared and is placed in the autoclave steam pressure of 21 kg/cm^2 is attained within 1 hour and is maintained for next three hours .
The mould is then removed from the autoclave and is tested for its size .
For OPC increase in size of any side must not exceed 0.8%.

Watch Video