Flakiness index and Elongation index test is not applicable to aggregate sizes smaller than:

Question

Question

This question was previously asked in

PGCIL DT Civil 2020 Official Paper

Answer 1

Concept:

Flakiness Index:

As per IS 2386 (Part 1):1963, cl. 4.0

The flakiness index of an aggregate is the percentage by weight of particles in it whose least dimension is less than 0.60 times their mean dimension.
This test is not applicable to a size less than 6.3 mm.

Elongation Index:

As per IS 2386 (Part 2):1963, cl. 5.0

The elongation index of an aggregate is the percentage by weight of particles in it whose greatest dimension is more than1.80 times their mean dimension.
This test is not applicable to a size less than 6.30 mm.

Additional Information

The following table shows the different test's acceptable limits on aggregates:

Aggregate Test	Acceptable Limit
Crushing test	Crushing Value: ≯ 30% for the surface course ≯ 45% for base course
Impact Test	Aggregate impact value: ≯ 30% for the surface course ≯ 35% for base course
Abrasion test	Abrasion value: ≯ 35% for Bituminous concrete ≯ 50% for the base course.
Soundness test	% loss in weight: ≯ 12% for Na₂SO₄ ≯ 18% for MgSO₄
Flakiness index test	% of aggregates passing through 0.6d_mean ≯ 15% of the total weight
Elongation Index test	% of aggregates passing through 1.8d_mean ≯ 15% of the weight of aggregates (after flakiness test)
Water absorption test	Water absorption ≯ 0.6% of the weight.