To convert kilograms (kg) of aggregate to cubic feet (cft), you need to consider the density of the aggregate. Based on the provided reference, which assumes a specific density, the conversion is straightforward.
According to the reference dated 27-Sept-2017:
1 kg contains 1/1650 cum.
This implies the density of the aggregate is approximately 1650 kg per cubic meter (cum).
The reference further calculates for a larger quantity:
1MT (Metric Tonne) = 1000 kg
1000 kg contains = 1000/1650 cum = 0.6061 cum.
To convert cubic meters (cum) to cubic feet (cft), a conversion factor is used (approximately 35.31 cft per cum).
= 0.6061 x 35.31 = 21.4 cft.
Therefore, 1000 kg of this aggregate is equivalent to 21.4 cft.
Understanding the Conversion
The conversion from a unit of mass (kg) to a unit of volume (cft) is not a fixed mathematical constant like converting inches to centimeters. It depends entirely on the density of the material being measured. Different types of aggregate (e.g., crushed stone, gravel, sand) have different densities, and even the same type can vary based on particle size distribution and moisture content.
The conversion provided in the reference (1000 kg = 21.4 cft) is based on an assumed bulk density of approximately 1650 kg/cum (or 1.65 tonnes/cum).
Conversion Factor Derived from Reference
From the reference's calculation (1000 kg = 21.4 cft), we can derive a conversion factor per kilogram for aggregate with this specific density:
1 kg = 21.4 cft / 1000 kg
1 kg ≈ 0.0214 cft
General Formula for Conversion
The general formula to convert weight to volume is:
Volume = Mass / Density
Where:
- Volume can be in cubic meters (cum) or cubic feet (cft).
- Mass is in kilograms (kg) or tonnes (MT).
- Density is the bulk density of the aggregate, typically measured in kg/cum or lbs/cft.
To get the volume directly in cubic feet from kilograms:
*Volume (cft) = Weight (kg) / Bulk Density (kg/cum) 35.3147 (cum to cft conversion factor)**
Using the reference's implied density (1650 kg/cum):
Volume (cft) = Weight (kg) / 1650 kg/cum 35.3147 cft/cum
Volume (cft) ≈ Weight (kg) 0.0214 cft/kg
Example Conversion
Let's convert 500 kg of aggregate using the conversion factor derived from the reference (based on 1650 kg/cum density):
Volume (cft) = 500 kg * 0.0214 cft/kg
Volume (cft) ≈ 10.7 cft
Alternatively, using the steps from the reference:
- Convert kg to cum: 500 kg / 1650 kg/cum = 0.3030 cum
- Convert cum to cft: 0.3030 cum * 35.31 cft/cum = 10.7 cft
Important Considerations
- Density Variation: The density of aggregate can vary significantly depending on the type, gradation, compaction, and moisture content. Typical bulk densities for dry aggregate can range from 1400 kg/cum to over 1700 kg/cum. Always use the actual density of the aggregate you are working with if possible.
- Moisture Content: Aggregate weight includes moisture. Wet aggregate weighs more than dry aggregate for the same volume. Conversions are often based on dry bulk density.
- Bulk vs. Solid Density: Conversions usually use bulk density, which accounts for the air voids between particles, rather than the solid density of the rock itself.
Conversion Table (Based on Reference Density ~1650 kg/cum)
This table shows approximate conversions using the 1 kg ≈ 0.0214 cft factor derived from the reference.
| Weight (kg) | Approximate Volume (cft) |
|---|---|
| 100 | 2.14 |
| 250 | 5.35 |
| 500 | 10.70 |
| 1000 (1 MT) | 21.40 |
Remember that this conversion is specific to the density assumed in the reference. For accurate conversions, determine the actual bulk density of your aggregate.
