Flakiness Index Test

 

The flakiness index of aggregates is determined by the percentage of flaky particles contained in it. For base course, and construction of asphalt and cement concrete types the presence of flaky particles is considered undesirable as it may cause inherent weakness with possibilities of braking down under heavy loads. Therefore, in pavement construction the flaky particles are to avoid particularly is surface course.

Thickness gauge

The test apparatus consists of a standard thickness gauge (6.30 – 63.0 mm) is used for this test. The flakiness index test (FI) is not applicable passing 6.30 mm or retaining 63.0 mm test sieve.

Testing procedure

The dried aggregates sample is allowed to passing and retained on a set of sieve.

The weight of retained aggregate on each sieve is measured and determined the percentage of retained.

Each of the particles fractions of aggregate is tried to passing through the slot of the thickness gauge.

The weight of aggregates passing on each gauge is measured.

Discarded the fraction of aggregate if it has the percentage of retained is less than or equal to 5 percent.

Then, the FI is the total weight of the material passing the various thickness gauges expressed as a percentage of the total weight of the sample gauged. The flakiness index value of the aggregate should be below 35 % that recommended for the road construction.

Calculation