Stone Testing – Purpose of Dorry’s Testing Machine In standard laboratory evaluation of building stones, the Dorry’s testing machine is specifically used to determine which property relevant to road and floor stones?
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ACrushing strength under compressive load
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BHardness/abrasion resistance of stone surfaces
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CImpact resistance under sudden loads
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DWater absorption by saturation
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ETensile splitting strength
Answer
Correct Answer: Hardness/abrasion resistance of stone surfaces
Explanation
Introduction:Different stone tests target different failure mechanisms. The Dorry’s testing machine is a classic apparatus used to rank stones for wear resistance—critical for road metal, flooring, and pavements subjected to traffic abrasion.
Given Data / Assumptions:
- Specimens are stone discs or cylinders prepared to standard sizes.
- Machine applies abrasive action under load using standardized materials.
- Loss in weight or thickness indicates wear.
Concept / Approach:
Hardness in this context reflects resistance to abrasion. Dorry’s test simulates grinding action, producing a quantifiable wear index. Materials with better hardness show less loss and are favored for surfacing where polish and durability matter.
Step-by-Step Solution:
1) Prepare stone specimens as per the method.2) Subject to abrasive action under prescribed load and revolutions.3) Measure loss in weight/volume to compute wear index.4) Interpret results: lower loss ⇒ higher hardness/abrasion resistance.Verification / Alternative check:
Materials testing manuals group Dorry’s test with other abrasion tests (e.g., Los Angeles) for comparative assessment of wear resistance.
Why Other Options Are Wrong:
Crushing, impact, and water absorption are measured via distinct apparatuses and procedures; Dorry’s machine is not designed for these properties.
Common Pitfalls:
Confusing abrasion tests with impact or compression tests; mislabeling the wear index as strength.
Final Answer:
Hardness/abrasion resistance of stone surfaces