The Soundness Test of cement, conducted using the Le Chatelier apparatus, is used to detect uncombined
- AAlumina and Iron oxide
- BSilica and Gypsum
- CLime and MagnesiaCorrect
- DAlkalies and Chlorides
Solution
Concept
Soundness of Cement
Formula
N/A
Step-by-step solution
1. Identify the objective of conducting the Soundness Test of cement using the Le Chatelier apparatus. 2. Recall that unsoundness and expansion in cement are caused by uncombined lime and magnesia. 3. Select Option (c) as the correct answer.
Explanation
The Le Chatelier apparatus tests the soundness of cement to ensure it does not expand excessively after setting. Expansion occurs when uncombined (free) lime or magnesia slowly reacts with water over time, causing cracking and structural weakness. Therefore, the test specifically checks for excess uncombined lime and magnesia.
Shortcut
To remember the soundness tests for cement, use the mnemonic "Le-Lime vs. Auto-Both": - Le Chatelier Test: Detects free Lime only. - Autoclave Test: Detects both free Lime and Magnesia.
Common mistake
A common mistake is assuming that the Le Chatelier test detects unsoundness caused by both free lime and magnesia. In reality, the Le Chatelier apparatus only detects unsoundness due to free (uncombined) lime, whereas the Autoclave test is required to detect unsoundness caused by both lime and magnesia.
Correct answer: C) Lime and Magnesia