Soundness Test of Cement
Certain cement shows expansion after setting and causes disruption of hardened mass. The testing of the soundness of cement is to ensure that the cement does not show any appreciable expansion after setting. Unsoundness of cement is due to excess of lime, magnesia and proportion of sulphate.
There is Le-Chatelier test to find out the soundness of cement. It consists of a small split cylinder of spring or brass or other suitable metal of 0.5 mm thickness forming a mould 30 mm internal diameter and 30 mm high. On either side of the split, two indicators are braced suitable with pointed ends made of 2 mm diameter brass wire AA such that the distance of these ends to the centre of the cylinder is 165 mm. the split cylinder is kept between the glass plate.
To detect the presence of uncombined lime in cement.
- Le-Chateliers Apparatus
- Glass Sheet – 2 Numbers
- Mixing Pan
- Water bath
- Take the 100gm cement sample.
- Add water to make a paste. the quantity of water should be 0.78 times of water taken for normal consistency.
- Now place the mould on a glass sheet and fill the mould with cement paste and put another glass sheet at the top of the mould and put a small weight on it at top.
- Now submerged the whole assembly in water for 24 hours temperature between 27 ± 20°C.
- Now measure the distance between the point of indicators is L1.
- Now the mould is again submerged in water and heats the water up to the boiling point about 25-30 minute and keep it boiling for 3 hours.
- After that remove the mould from the water allow it to cool at room temperature for one hour then measure the distance between indicators point L2.
- The difference between these two measurements is the expansion of cement.
Soundness/expansion of cement = L1-L2
L1=Measurement is taken after 24 hours of immersion in water at a temp. of 27 ± 20°C
L2=Measurement was taken after 3 hours of immersion in water at boiling temperature.
Calculate the mean values of two measurements, to the nearest 0.5 mm. This value must not exceed 10 mm for ordinary portland cement.
|Name of Cement||Standards||Expansion(max)|
|Rapid Hardening Cement||IS8041-1990||10mm|
|Low heat cement||IS12600-1989||10mm|
|PPC Cement||IS1489-1991 part -1||10mm|
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