A cement is said to be unsound if the hydration of a hardened paste of it is eventually accompanied by excessive expansion, causing cracking and reduction in strength.
Accelerated hydration procedures are used routinely in cement production to check that it does not possess this property. The simple apparatus devised by Le Chatelier is used to indicate the expansion of a paste.Here we will discuss about the practical of soundness test of cement
IS 4031 PART 3
- To determine the soundness of cement.
- The apparatus for conducting Le-Chatter test shall conform to IS: 5514 – 1969.
- Balance of capacity 500 grams and sensitivity 0.01gms.
- Water bath capable of raising the temperature from 27+ 20C to boiling point in 27 + 3 minutes.
- Take representative sample of cement and mix with 0.78 times the water required to give a paste of standard consistency as per IS: 4031 (Part 4) 1988.
- Place a lightly oiled mould on a lightly oiled glass and fill it with this cement paste.
- Prepare the paste in a manner and under the conditions all as per IS: 4031 (Part 4) 1988.
- Keep the edges of the mould gently together during this operation.
- Cover the mould with another piece of lightly oiled glass sheet and place a small weight.
- Immediately submerge the whole assembly in water bath maintained at a temperature of27 + 20C and keep there for 24 hours.
- After 24 hours remove the mould from the water bath and measure the distance separating the indicator points (E1).
- Again submerge the whole assembly in water bath at a temperature of 27 + 20C and bring the water to boiling in 27 + 3 minutes and keep it for 3 hours.
- Remove the mould from the water bath, allow it to cool and measure the distance between the indicator points (E2).
- The distance between the two measurements indicates the expansion of the cement.
- Make at least two determinations for each test.
- Calculate the Soundness of cement from the equation given below
Soundness = E2 – E1
E1= Initial distance between the indicator points.
E2= Final distance between the indicator points.
Report the individual and the mean results to the nearest 0.5mm.
- Take care to maintain the temperature of the moulding room, dry material and water within 27 + 20C and the humidity of the laboratory within 65 + 5%.