Flakiness Index Test and Elongation Index Test on Aggregates

Coarse aggregate constitutes the biggest part of concrete. It is desirable that aggregates are of desired properties. Two shape tests namely Elongation Index Test and Flakiness Index Test are used for selection of proper aggregates.

Flakiness Index

It is the percentage by weight of particles in it whose least dimension is less than three-fifth of their mean dimension.

Determine the Flakiness Index

Apparatus for test

Balance
Metal Gauge

Procedure for Flakiness Index Test

At first, the sample is sieved with an Indian standard sieve.

Then each fraction of sieved material is gauged in turn on Flakiness Index. The total amount passing the
gauge shall be weighed to an accuracy of at least 0.1 percent of the weight of the test sample.

This test does not apply to sizes smaller than 6.3 mm.

Elongation Index

The Elongation Index is the percentage by weight of particles whose greatest dimension is greater than 1.8 times its mean dimension. The test applies only to aggregates whose least dimension is not smaller than 6.3 mm.