The figure given below represents a collapse slump pattern (concrete completely collapses and spreads sideways). This represents a:
Correct Answer: D. Collapse slump of concrete
📚 Detailed Explanation: Types of Slump
After removing the slump cone, the shape of concrete deformation classifies the slump into three types based on the mechanism of collapse.
Why D (Collapse slump) is correct: A collapse slump occurs when the concrete is so wet and fluid that it completely collapses and spreads outward (shears in all directions equally), rather than simply subsiding vertically. This indicates very high w/c ratio, excessive workability, and probable segregation or bleeding. Options A (low slump = very slight vertical drop), B (normal/true slump = clean vertical settlement), C (shear slump = one side shears off, indicating asymmetric failure).
Types of Slump
| Type | Behaviour | Interpretation |
|---|---|---|
| True/Normal slump | Uniform vertical settlement | Cohesive mix, acceptable |
| Shear slump | Top half shears off sideways | Lack of cohesion, poorly graded |
| Collapse slump | Complete spread outward | Excessively wet mix |
- Only the true slump gives a valid workability measurement; shear and collapse slumps indicate mix problems.
- Collapse slump = too wet → reject and redesign the mix with lower w/c.