Flakiness & Elongation Index — Lab Manual
Flakiness & Elongation Index: objective, apparatus, step-by-step procedure, formulas, typical values and a printable data sheet (BS 812-105).
Objective & standard
Shape of coarse aggregate — flaky and elongated particles weaken concrete and asphalt.
Standard: BS 812-105
Apparatus
- Thickness gauge & length gauge
- Sieves 63 … 6.3 mm
- Balance
Procedure
- Sieve the sample into size fractions.
- Pass each fraction through the matching slot of the thickness gauge; weigh the flaky part.
- Pass the non-flaky part over the length gauge; weigh the elongated part.
- Total for all fractions.
Calculations
- FI = mass passing thickness gauge ÷ total × 100
- EI = mass retained on length gauge ÷ non-flaky mass × 100
Typical values: Concrete FI ≤ 25–35 %; asphalt combined FI + EI ≤ 30–35 %.
Data sheet (print this page)
Project: ____________________ Sample: __________ Date: __________ Tested by: __________
| Fraction (mm) | Mass (g) | Flaky (g) | Elongated (g) |
|---|---|---|---|
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