Elongation Index
IS 2386 (Part 1)
Each particle is passed through a length gauge to identify elongated (needle-like) pieces, and the elongation index is calculated as the combined weight of elongated particles as a percentage of the total sample.
Like flakiness, high elongation reduces interlock and workability and increases the risk of particle breakage under load, so it is controlled alongside the flakiness index — the combined "flakiness and elongation index" is often specified as a single limit.