Correct option is C
if the values are more than 10 mm, then the cement is unsound.
The soundness test using Le Chatelier's apparatus is a standard test to determine the soundness of cement. Soundness refers to the ability of the cement to retain its volume after setting without delayed expansion, which could cause structural issues such as cracking.
Le Chatelier's Apparatus:
The apparatus consists of a split brass mould, which is in the form of a cylindrical ring. The mould is placed on a glass plate, and a cement paste is filled into the mould.
The mould is then covered with another glass plate and immersed in water for 24 hours.
The sample is heated to boiling for a specific period, typically 25 to 30 minutes, and then kept at boiling temperature for 3 hours.
Purpose of the Test:
The purpose of this test is to detect the presence of uncombined lime or magnesia, which can cause the cement to expand after setting. This expansion can lead to instability, cracking, or even failure of structures.
Measurement:
After the test, the distance between the pointers on the Le Chatelier mold is measured. The initial distance between the pointers is recorded before the test, and the final distance is measured after the test.
The difference between these two measurements gives the expansion of the cement.
Acceptable Range:
According to standard testing practices, the expansion should not exceed 5 to 10 mm. If the expansion is within this limit, the cement is considered to be sound and suitable for use. If the expansion exceeds 10 mm, the cement is considered unsound, meaning it could cause potential problems in the structure due to excessive delayed expansion.
