What is flakiness index of coarse aggregate?

What is flakiness index of coarse aggregate?

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.

What is flakiness and elongated index of coarse aggregate?

The Flakiness Index is the total weight of the material passing the various thickness gauges or sieves, expressed as a percentage of the total weight of the sample gauged. Separation of Elongated Material- Each fraction shall be gauged individually for length on a metal length gauge of the pattern shown in Fig. 4.

How do you determine the presence of a flaky particle?

Flakiness index gauge The weight of particles passing the thickness gauge is recorded for each fraction. This will be the weight of flaky particles. The flakiness index is calculated by expressing the weight of flaky particles as a percentage of total weight of the sample.

What is meant by coarse aggregate?

Coarse aggregates refer to irregular and granular materials such as sand, gravel, or crushed stone, and are used for making concrete. In most cases, Coarse is naturally occurring and can be obtained by blasting quarries or crushing them by hand or crushers.

Why flakiness index test is done?

The test Flakiness index of aggregate is used to determine the particle shape of the aggregate specimen and each particle shape being preferred under specific condition.

What is the limit of flakiness index?

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

Sl No. Type of Pavement Maximum limit of flakiness index in %
1 Bituminous carpet 30
2 (i) Bituminous / Asphaltic concrete 25

Is sieves for coarse aggregate?

Coarse aggregate means the aggregate which is retained on 4.75mm sieve when it is sieved through 4.75mm. To find fineness modulus of coarse aggregate we need sieve sizes of 80mm, 40mm, 20mm, 10mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm and 0.15mm.

How do you perform a flakiness index test?

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.

Where is flakiness used?

Flakiness Index of aggregate is the percentage by weight of aggregate particles whose least dimension is less than 0.6 of their mean dimensions. This test is applicable to aggregates having size larger than 6.3mm.

What is an example of coarse aggregate?

Coarse aggregates are a construction component made of rock quarried from ground deposits. Examples of these kinds of ground deposits include river gravel, crushed stone from rock quarries, and previously used concrete. Coarse aggregates are generally categorized as rock larger than a standard No.

What is the flakiness index of an aggregate?

The Flakiness index of aggregates is the percentage by weight of particles whose least dimension (thickness) is less than three- fifths (0.6times) of their mean dimension.

What is the importance of flakiness and elongation index?

Flakiness and Elongation Index Test are very important tests to be performed on aggregate in the laboratory. This test gives the percentage of flaky and elongate aggregate present in the total aggregate sample.

What should flakiness index be for base coarse construction?

Flaky and elongated particles are considered undesirable for base coarse construction as they may cause weakness with possibilities of braking down under heavy loads. BS-1241 specifies a Flakiness index not exceeding 30% irrespective of the aggregate size.

How is the elongation index of an aggregate determined?

Thus the evaluation of the shape of the particles, particularly concerning flakiness, elongation is necessary. The flakiness index of aggregates is the percentages by weight of particles whose least dimension (thickness) is less than 3/5 th (0.6) of their mean dimension.