Elongation Index for Aggregate Classification

For determining elongation index. Particle is elongated when its length (longest dimension) is more than 1.8 of the mid-size of the sieve fraction. Aggregate to be classified is separated into seven sieve fractions from 63 to 6.3mm, and each fraction is examined separately. Six labeled openings between pairs of metal pins measure particle from each of the six sieve cuts below 50mm. The mass of all elongated particles (failing to pass between pins) as percent of the sample is the elongation index.