How do you find flakiness and elongation index?

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 =________(%)

What is flakiness and elongation index?

Flakiness Index is the percentage by weight of particles in it, whose least dimension (i.e. thickness) is less than three-fifths of its mean dimension. Elongation Index is the percentage by weight of particles in it, whose largest dimension (i.e. length) is greater than one and four-fifths times its mean dimension.

Which gauge is used for flakiness index?

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.

How do you calculate flakiness?

CALCULATIONS

4.1. Calculate Flakiness Index:
Flakiness Index = Passing Sample Particle Count.
× 100. Retained Sample.
Particle Count. +
Passing Sample. Particle Count.
4.2 Report the Flakiness Index to the nearest whole number.

How the flakiness index and elongation index values are determined in the laboratory?

The flakiness index of an aggregate sample is found by separating the flaky aggregates by sieving. Flakiness index is expressed as their weight as a percentage of the weight of the sample tested. The Elongation index of an aggregate sample is found by separating the elongated aggregates by sieving.

What is a flakiness index?

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.

How is flakiness index expressed?

Flakiness Index of aggregate is the percentage by weight of aggregate particles whose least dimension is less than 0.6 of their mean dimensions. 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.

What is elongation index?

Elongation index of an aggregate is the percentage by weight of particles whose greatest dimension (length) is greater than one and four-fifth times (1.8 times or 9/5 times) their mean dimension. It is measured on particles passing through mesh size of 63mm and retained on mesh size of 6.3mm.

Why do we determine flakiness index?

This test is used to determine the particle shape of the aggregate and each particle shape being preferred under specific conditions. The significance of flakiness & elongation index is as follows; Due to high surface area to volume ratio, the flaky and elongated particles lower the workability of concrete mixes.