In the last 30 years multi-layer elastic theory has been applied with some success to the design of flexible pavements, and particularly those with cemented bases. During 1984-1985 the involvement of the authors in an investigation of the performance of some 2000km of very variable strength concrete roads in the Philippines carrying very heavy wheel-loads made it essential to develop a theoretical design procedure relating axle loading, pavement thickness and concrete strength. The present paper arises from that work.