*It is very important that cement after setting shall not undergo any appreciable change of volume. The determination of Soundness of cement is necessary to ensure that the cement does not show any appreciable subsequent expansion.
*The unsoundness in cement is due to % of excess of lime than that could be combined with acidic oxide at the kiln, excess of magnesia or excessive proportion of sulphates.
*Soundness of cement is determined by the Lechatelier Test.
*It consists of small split cylinder of brass 05 mm thick. This forms a mould 30 mm. internal diameter and 30 mm high. On each side of split is attached an indicator having pointed end. Distance between the centre of the cylinder and the pointed end of each indication is 165 mm.
*The cement paste having 0.78 P water is filled in lechatelier apparatus and covered by glass plate at both ends and kept in water for 24 hrs. Measure the distance between indicator in mm. Again keep the assembly in boiling water for an hour. Allow it to cool and measure the distance between the indicator in mm. The difference between first and this reading gives the soundness of cement. It should not exceed 10 mm.
