ASTM C 29/C 29M – Standard Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate

This standard describes the procedure for determining the bulk density, also known as the unit weight, of aggregates whether in a loose or compacted condition. Additionally, it lays out methods to calculate the void contents between particles in aggregates which can be applied to fine, coarse, or mixed aggregates. The test is suitable for aggregates with a nominal maximum size not exceeding 5 inches (125 mm).

Significance and Use

1. Bulk density values acquired through this test method are pivotal for selecting proper proportions in concrete mix design.
2. These values are also instrumental for understanding mass-to-volume relationships used in commercial agreements.
3. Bulk density on dry basis is determined by this test; note that field conditions may vary due to moisture and compaction levels.

Apparatus Required

• Balance: Accurate to 0.1% of the test load and graduated to at least 0.1 lb (0.05 kg).
• Tamping Rod: A straight steel rod, 5/8 in. (16 mm) in diameter, with rounded ends.
• Measure: A cylindrical metal measure, ideally with handles, rigid, and watertight.
• Shovel or Scoop: For transferring aggregate into the measure.
• Calibration Equipment: Includes a piece of plate glass and grease for calibration.

Procedures

The process involves multiple procedures such as:

1. Calibration of the measure with water.
2. Selection of the appropriate procedure for bulk density – shoveling, rodding, or jigging based on aggregate size.
3. Filling and rodding the measure in thirds, taking care not to impact forcefully with the rod on the bottom or previously compacted layers.
4. For jigging, layers are compacted by alternate dropping of the measure.
5. Shoveling involves careful addition of aggregate to avoid particle segregation.

Calculations and Report

• Bulk Density: Calculate using the formulas provided (M = (G – T) / V or M = (G – T) * F).
• SSD Bulk Density: Adjust the oven-dry bulk density with the absorption rate to obtain SSD condition density.
• Void Content: Assess based on the bulk density and using the formula detailed (Voids = 100 * (S * W – M) / (S * W)).

Finally, report the results for bulk density rounded to the nearest 1 lb/ft³ [10 kg/m³].

The detailed and precise execution of this test method ensures reliability in assessing the properties of aggregate materials for construction and engineering purposes.

ASTM C29/C29M is a standard test method for the bulk density (“unit weight”) and voids in aggregate.

1. Bulk Density
2. Unit Weight
3. Voids in Aggregate
4. Aggregate
5. Loose Bulk Density
6. Compacted Bulk Density
7. Test Method
8. Standard Test
9. Gravel
10. Sand
11. Crushed Stone
12. Specific Gravity
13. Voids Ratio
14. Density Measurement
15. Material Testing
16. Cylindrical Measure
17. Tamping Rod
18. Mechanical Shaker
19. Rodded Density
20. Loose Density
21. ASTM International
22. Construction Materials
23. Coarse Aggregate
24. Fine Aggregate
25. Test Procedure
26. Laboratory Test
27. Field Test
28. Aggregate Handling
29. Testing Standards
30. Civil Engineering