A conspectus of aggregate strength and the relevance of this factor as the basis a physical classification of crushed rock aggregate. Conference. 6F, 1T, 7R : Spence, IM Univ. Dundee, Scotland, GB Ramsay, DM Univ. Dundee, Scotland, GB Dhir, RK Univ. Dundee, Scotland, GB 6F, 1T, 7R. Proc. Third Congress Int. Soc. Rock Mech. Denver, 1974, V2, Part A, 1974,