Created: 2025/06/29 21:46
Experiment No.: 02
Name of Experiment: Determination of Flakiness Index of Aggregate Sample
Method: BS 812 (Part 1)
Objectives of the Test:
- To determine the Flakiness Index (F.I.) of a given aggregate sample.
- To assess the shape characteristics of coarse aggregates.
- To evaluate the suitability of aggregates for use in asphalt and concrete mixes.
Significance of the Test:
- Flaky particles reduce the strength and workability of mixes.
- This test helps in selecting appropriate aggregate shapes for different construction purposes (e.g., concrete and asphalt).
- Ensures compliance with standards for aggregate quality.
- Influences workability, compaction, and strength of mix designs.
Apparatus Used:
- Oven
- Balance
- Sieve shaker
- Tray
- Thickness gauge
- Sieves
Datasheet:
Test Result:
The obtained Flakiness Index for the aggregate sample was 20.55%.
Discussion:
The flakiness index of the given aggregate sample was found to be 20.55%. This value indicates that about one-fifth of the aggregate particles are flaky, meaning they have a thin, flat shape relative to their other dimensions. In asphalt surfaces, this amount of flakiness is generally acceptable (standard is less than 30%). However, the standard for concrete works requires a much lower flakiness index (2.5% or less) because flaky particles can reduce the strength and durability of the hardened concrete.
This result is useful for deciding whether such particle may be used for a construction project. However, the flakiness index does not give a complete picture of aggregate quality—it only addresses particle shape. Other factors like angularity, and strength also play important roles in performance.
The assumed conditions for the test—such as proper sieve sizing, and adequate sample mass per fraction appear to have been met. Each size fraction exceeded the minimum mass required (5%), and flaky particles were identified using the thickness gauge.
There are some limitations and potential sources of error in this test. Inaccurate weighing, improper sieving, or misjudging particles that barely pass through the gauge can affect the result. Also, human error in classifying borderline particles may slightly skew the value. Despite these, when performed carefully, the test provides a fairly reliable estimate of flakiness for practical use.