Units in materials management: Bulk density (unit weight) of aggregates at the stockyard or in batching is typically expressed in which unit?
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Atonnes per cubic metre
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Bkg per cubic metre
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Ckg per litre
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Dg per cm3
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ENone of these
Answer
Correct Answer: kg per cubic metre
Explanation
Introduction / Context:Bulk density of aggregates is needed for volumetric batching, truck payload checks, and storage calculations. Consistent units prevent errors in converting between weight and volume on site.
Given Data / Assumptions:
- Bulk density measured in a container by filling and weighing.
- Moisture and compaction condition stated (loose or rodded).
- Construction site practice favors SI units.
Concept / Approach:In SI practice, bulk density is expressed as kg/m^3. While g/cm^3 or tonnes/m^3 are dimensionally equivalent, routine batching and mix design documentation typically use kg/m^3 to align with cement and water units and ready-mix ticketing.
Step-by-Step Solution:Select the SI unit used in mix design tables and stock records → kg/m^3.Recognize equivalence: 1 g/cm^3 = 1000 kg/m^3, 1 tonne/m^3 = 1000 kg/m^3.Prefer kg/m^3 for standardization.
Verification / Alternative check:Material datasheets and codes list typical bulk densities (e.g., sand ~1500–1700 kg/m^3) in kg/m^3.
Why Other Options Are Wrong:They are not the most commonly adopted unit in site batching documentation, even if convertible.
Common Pitfalls:Mixing up dry-rodded vs loose densities; neglecting moisture correction when converting volume to mass.
Final Answer:kg per cubic metre.