1. Earland, M.G. and Pike, D.C. ‘Stability of gravel sub-bases’, RR64 (Transport and Road Research Laboratory, U.K., 1985).
2. Specification for Highway Works (Department of Transport, U.K. H.M.S.O., 1986).
3. British Standard 5835, ‘Compactibility test for graded aggregates’, (British Standard Institution, London).
4. Bolton, M.D. ‘The strength and dilatancy of sands’,Geotechnique 36 (1) (1986) 65–78.
5. Head, K.H., ‘Manual of Soil Laboratory Testing’, Vol. 1. ‘Soil classification and compaction tests’ (Pentech Press, London, 1980).