BS 812-105.2:1990

This British Standard, a part of the BS 812 series, describes the method for determining the elongation index of coarse aggregate.

Aggregate particles are classified as elongated when they have a length (greatest dimension) of more than 1.8 of their mean sieve size, this size being taken as the mean of the limiting sieve apertures used for determining the size fraction in which the particle occurs. The elongation index is found by separating the elongated particles and expressing their mass as a percentage of the mass of sample tested. The test is not applicable to material passing a 6.30 mm test sieve or retained on a 50.0 mm test sieve.