Abstract

From mid 1951 to mid 1954 I worked in Africa with consultant engineers Scott & Wilson (S&W) in the then Nyasaland Protectorate (now Malawi). Failure of clayey laterite in Chileka airfield pavement had led S&W to specify use of costly crushed-stone in subsequent pavement construction. After my tests showed that 3% of slaked lime reduced the plasticity index of clayey lateritic gravel, I built a successful experimental pavement of stabilised gravel. I had to develop air-photo location of gravel borrow-pits before road pavements could be constructed of stabilized gravel, but road-cost/mile was halved in 1954/5 S&W contracts. As a research student in 1954/5 I found that published shear box and triaxial test paths of disturbed soil (both drained and undrained) approached a CS line, from which it later (1) followed that a compact aggregate of grains can act as a plastic continuum; should this new understanding alter geotechnical engineer’s performance or costs?