Created: 2025/06/30 00:46
Experiment No.: 03
Name of Experiment: Determination of Angularity Number of Aggregate
Method: BS 812, Part 1 Clause: 7.5 & BS 812, Part 2 Clause: 5
Objectives of the Test:
- To determine the angularity number of a given coarse aggregate sample.
- To assess the shape characteristics of aggregates in terms of void content.
- To evaluate aggregate suitability for use in construction projects.
Significance of the Test:
- Angularity affects the workability and handling of concrete and asphalt mixes.
- Affects the stability of mixtures that rely on interlocking of the particles.
- Useful in quality control and aggregate source comparison.
Apparatus Used:
- Cylindrical metal container
- Metal tamping rod
- Balance
- Metal scoop
Datasheet:
Test Result:
The Angularity Number (A.N.) of the given sample was determined to be 4.
Discussion:
The angularity number of the aggregate sample was found to be 4. This value indicates that the void content in the aggregate sample is moderately higher than that of perfectly rounded aggregates, suggesting that the particles have a fair amount of angularity. This is well within the standard limit of angularity (0 - 12) and is beneficial for applications like asphalt or concrete mixes where better interlocking and resistance to movement under load are desired.
The angularity number helps compare aggregate shapes and their packing efficiency. Rounded aggregates tend to settle better and have lower angularity numbers (close to 0), while more angular aggregates occupy more space and have higher angularity numbers (closer to 12). The obtained value of 4 suggests that the aggregate is not highly angular but still offers better interlocking than very smooth particles.
The assumed conditions for the test were likely met. The aggregate was oven-dried and filled into the cylinder while compacted by free-falling tamping rod from 2" height, 100 * 3 times. Afterwards, the container was filled with water very carefully to the right level.
Potential errors could arise if the cylinder was not filled uniformly, if water measurements were inaccurate, or if the aggregate was not fully dried. Also, inconsistent tamping or slight compaction could skew the volume and therefore the angularity number. Nonetheless, with careful handling, the result is reasonably reliable.