The aggregate is said to be flaky when its least dimension is less than 3/5th (or 60%) of its mean dimension. Mean dimension is the average size through which th particles pass and the sieve size on which these are retained. For example, mean size of the particles passing through 25 mm sieve and retained on 20 mm sieve is (20+25)/2=22.5 mm. if the least dimension is less than 3/5 x (22.5) = 13.5 mm, then the material is classified as flaky. Flaky aggregate tends to be oriented in one plane which affects the durability.