Slump Test Apparatus – identify the incorrect statement Regarding the standard slump cone used in the slump test for concrete, which statement below is incorrect?
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AThe bottom and top ends of the slump mould are parallel to each other
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BThe axis of the mould is perpendicular to the end faces
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CThe internal surface of the mould is kept clean and free from set cement
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DThe mould is in the form of a frustum of a hexagonal pyramid
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ENone of these
Answer
Correct Answer: The mould is in the form of a frustum of a hexagonal pyramid
Explanation
Introduction / Context:The slump test assesses workability by measuring the subsidence of concrete after removing a standard mould. Accurate results depend on a correctly shaped and maintained mould and proper test procedure.
Given Data / Assumptions:
- Standard slump cone (Abrams cone).
- End faces are nominally parallel and the axis is normal to them.
- Clean internal surface ensures friction does not bias results.
Concept / Approach:The slump mould is a frustum of a right circular cone (not a hexagonal pyramid). The standard dimensions are typically 200 mm top diameter, 300 mm height, and 100 mm bottom diameter, with smooth internal surface.
Step-by-Step Solution:Identify the geometric shape required by the standard: frustum of a right circular cone.Compare each statement to the standard specification.Only the hexagonal pyramid statement conflicts with the requirement.
Verification / Alternative check:Inspection of certified slump cones confirms circular cross-sections; hexagonal forms are not used in the standard test.
Why Other Options Are Wrong:
- (a) and (b) describe correct geometry/tolerances.
- (c) is essential good practice for repeatable results.
- (e) cannot be correct because one incorrect statement exists.
Common Pitfalls:Using dented or out-of-round cones or dirty interiors can give misleading slump values; always verify apparatus condition.
Final Answer:The mould is in the form of a frustum of a hexagonal pyramid