Get How To Determine Flakiness Index

Flakiness index and elongation index test is not applicable to aggregates size smaller than 6.3 mm. Permissible value should not exceed 35−40% of flakiness and no limit decided for elongation index.

The flakiness index of an aggregate sample is found by separating the flaky particles and expressing their mass as a percentage of the mass of the sample tested. The test is not applicable to materials passing the 6.30 mm test sieve or retained on the 63.00 mm test sieve.

Thickness Gauge is used to determine if the aggregate particles are to be considered as flaky, i.e. their thickness is less than 0.6 of their nominal size. The aggregate to be classified is separated into seven sieve fractions from 6.3 to 63 mm, and each fraction is examined separately.

6. calculation The Flakiness Index on an aggregate is = Total weight passing Flakiness Gauge x 100 / Total weight of test sample =_________(%) The Elongation Index on an aggregate is = Total weight retained on Elongation Gauge x 100 / Total weight of test sample =________(%)

Length Gauge (Elongation Index) Thickness Gauge (Flakiness Index) is a slotted stainless steel gauge for rapid hand trying of particles from the seven sieve fractions to determine the flakiness index.

A flakiness index test is conducted to determine the shape of the aggregates. The presence of flaky or flattened coarse aggregates is undesirable in cement concrete, in making bituminous roads, & in the construction of pavements. Flaky-shaped aggregates are weak in creating a good bond & compaction in the concretes.

Then the flakiness index is calculated as the total weight of material passed through various thickness gauges, expressed as a percentage of total weight of the sample gauged. Flakiness Index of aggregates used in road construction should be less than 15% and normally does not exceed 25%.

The flakiness index is defined as the percentage (by mass) of stones in an aggregate having an ALD of less than 0.6 times their average dimension. Flaky aggregates tend to produce seals with less voids due to their tendency to pack more tightly than cubical aggregates, consequently flaky particles require less binder.

It is desirable that the flakiness index of aggregates used in road construction is less than 15% and normally does not exceed 25%. Elongation index value in excess of 15% percent is considered undesirable, however no recognized limits have been laid down for elongation index.