What is the purpose of flakiness and elongation test?

What is the purpose of flakiness and elongation test?

This test gives the percentage of flaky and elongate aggregate present in the total aggregate sample. Aggregate shape, size, and surface texture majorly affect the properties of freshly mixed concrete more than the properties of hardened concrete.

What is the significance of flakiness index 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.

What do you infer from flakiness test?

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 effect of flaky and elongated aggregates?

The results reveal that the effect of elongated aggregates is more than flaky aggregates, on the characteristic compressive strength of concrete. Concrete with 1:1 ratio of flaky to elongated aggregates possesses minimum weight.

Why is flakiness test required?

The Significance of Flakiness Index and Elongation Index Test of Aggregate. 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.

Why flaky or elongated particles are avoided in pavement construction?

Theory of Flakiness Index and Elongation Index Tests For base course and construction of bituminous and cement concrete types, the presence of flaky and elongated particles are considered undesirable as these cause inherent weakness with possibilities of breaking down under heavy loads.

How are flakiness index and elongation index values 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 meant by elongation index?

elongation index (I E) The percentage by weight of particles whose long dimension is greater than 1.8 times the mean dimension measured with a standard gauge. The elongation, n, is length divided by breadth and the elongation ratio is 1/n. A Dictionary of Earth Sciences. “elongation index .”

Why flaky and elongated aggregates are not preferred in construction?

Due to high surface area to volume ratio, the flaky and elongated particles lower the workability of concrete mixes. Flaky and elongated particles are considered undesirable for base coarse construction as they may cause weakness with possibilities of braking down under heavy loads.

Why flaky and elongated particles are avoided in pavement construction?

It is evident that the flaky and elongated particles will have less strength and durability when compared with cubical, angular or rounded particles of the same aggregate. Hence too flaky and too much elongated aggregates should be avoided as far as possible.

Why elongation index test is conducted?

If elongated particles are used for pavement base course construction, they may break down easily under heavy loads which will cause damage to the pavement. So, it is necessary to know the elongation index of given aggregate mix.

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

How to determine the flakiness and elongation index of coarse aggregates?

To determine the Flakiness and Elongation Index of Coarse Aggregates. The particle shape of aggregates is determined by the percentage of flaky (layered) and elongated particles contain in it.

What is the effect of elongation and flakiness on concrete particles?

For base course and construction of bituminous and cement concrete types, the presence of flaky and elongated particles are considered undesirable as these cause inherent weakness with possibilities of breaking down under heavy loads. Thus, evaluation of shape of the particles, particularly with reference to flakiness and elongation is necessary.

How to calculate flakiness index of concrete?

Flakiness Index = Weight of aggregate passed through width gauge 10 mm to 6.3 mm (W2) / Total weight of aggregate sample taken (W1) = (W2/W1) x 100 For example, Weight of aggregate passed through width gauge of 10 mm to 6.3mm (W2) = 200 gm and Total weight of aggregate sample = 1000 gm Flakiness Index = (200 gm / 1000 gm) x 100 = 20%

What is flakiness and elongation Index test?

Flakiness and Elongation Index Test 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.