The diameter of a cylinder in the Le-Chatelier apparatus for conducting the soundness test of cement is :
🔬 Understanding the Soundness Test and Le-Chatelier Apparatus
The soundness of cement refers to its ability to resist volume change after it has set. A cement that expands significantly upon setting is considered "unsound" and can cause cracking and disintegration of the structure. This expansion is primarily caused by an excess of uncombined (free) lime and magnesia in the cement. The Le-Chatelier apparatus is the standard equipment used to measure the potential expansion due to free lime.
📝 Detailed Analysis of the Apparatus Dimensions
(d) 30 mm
This is the correct answer. The Le-Chatelier apparatus consists of a small, split brass cylinder with two long indicator arms attached. The key dimensions of this cylinder are precisely specified: its internal diameter is 30 mm and its height is also 30 mm. The thickness of the brass wall is 0.5 mm. When a cement paste is placed inside and it expands, it forces the split cylinder open, and the movement of the indicator arms magnifies this expansion, which is then measured.
(a) 40 mm, (b) 22 mm, & (c) 35 mm
These are incorrect. These values do not correspond to the specified diameter of the Le-Chatelier cylinder. It's important to remember the specific dimensions as they are standardized for test consistency worldwide.
📊 Summary: Le-Chatelier Apparatus Specifications
| Parameter | Specification | Purpose |
|---|---|---|
| Internal Diameter | 30 mm | Standardized volume for the cement paste sample. |
| Height | 30 mm | Standardized volume for the cement paste sample. |
| Wall Thickness | 0.5 mm | Ensures it is flexible enough to open upon expansion. |
| Indicator Arm Length | 165 mm | Magnifies the small expansion for accurate measurement. |
| Max Expansion (OPC) | Should not exceed 10 mm | Acceptance limit for good quality cement. |
| Max Expansion (High Alumina) | Should not exceed 5 mm | Stricter limit for this type of cement. |
💡 Study Tips
- The "30-30" Rule: A simple way to remember the core dimension is that the Le-Chatelier cylinder is 30 mm in diameter and 30 mm high. It's a perfect cylinder.
- Soundness = Le-Chatelier: Create a direct mental link between the property "Soundness" and the apparatus "Le-Chatelier".
- Visualize the Test: Imagine the small brass cylinder being filled with paste. As the paste expands, it pushes the cylinder open, and the long arms move apart. The distance between the tips of the arms is what's measured, and it shouldn't be more than 10 mm for OPC.