What is the height of a slump cone mould used for testing the workability of the concrete?
Correct Answer: C. 30 cm
📚 Detailed Explanation: Slump Cone Dimensions
The slump cone (also called the Abrams cone) is a frustum of a cone with standardised dimensions per IS 1199. Memorising all three dimensions — top diameter, bottom diameter, and height — is frequently tested.
Why C (30 cm) is correct: The slump cone is a frustum (truncated cone) with:
• Top diameter = 10 cm (100 mm)
• Bottom diameter = 20 cm (200 mm)
• Height = 30 cm (300 mm)
The height of 30 cm is the critical measurement because it determines the volume of concrete tested and the reference height from which slump is measured. The base (20 cm) sits on the surface; the top (10 cm) is where concrete is fed in. After removing the mould, slump = 300 mm − final height of concrete.
• Top diameter = 10 cm (100 mm)
• Bottom diameter = 20 cm (200 mm)
• Height = 30 cm (300 mm)
The height of 30 cm is the critical measurement because it determines the volume of concrete tested and the reference height from which slump is measured. The base (20 cm) sits on the surface; the top (10 cm) is where concrete is fed in. After removing the mould, slump = 300 mm − final height of concrete.
Slump Cone Dimensions (IS 1199)
| Dimension | Value |
|---|---|
| Top diameter | 10 cm (100 mm) |
| Bottom diameter | 20 cm (200 mm) |
| Height | 30 cm (300 mm) |
| Tamping rod diameter | 16 mm |
| Tamping rod length | 60 cm |
| Number of layers | 3 |
| Strokes per layer | 25 |
- Slump = 300 mm − height of slumped concrete after removing mould.
- Memory aid: Top 10, Bottom 20, Height 30 (multiples of 10).