The Soundness Test is performed to detect the presence of uncombined lime and magnesia in cement. This test is conducted in Le Chatelier’s apparatus (Fig. 6.7). It consists of a small brass cylinder of 30 mm diameter, 30 mm height and 0.5 mm thickness, which is split along its generation with the split not exceeding 0.5 mm. On either sides of the split, two indicators with pointed ends are provided.
Figure 6.7 Le Chatelier’s apparatus
The cement paste is prepared with water content at consistency. The cylinder is placed over a glass plate and is filled with the cement paste. It is covered with another glass plate on the top. The whole assembly is immersed in water at 24–35°C for 24 hours. After 24 hours, the gap between the indicators is measured.
The mould with the specimen is immersed in water again and boiled for 30 minutes. After boiling for 1 hour, the mould is taken out and cooled. Again the gap between the indicators is measured after the end of cooling. The increase in gap represents the expansion of cement.
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