THE CHARACTERISTICS OF MATERIALS FOR THE DESIGN OF FLEXIBLE PAVEMENT STRUCTURES

An important part of the develpment of a structural design approach to the design of flexible pavements is adequate characteriation of the constituent materials in the contest of the part they play in the pavement structure. This characterisation should take the from of the determination of elastic constants and failure criteria so that linear elastic theory may be used to compute critical stresses and strains and the acceptability of these may be assessed in terms of the anticipated life of the pavement. The characteristics of bitumen bound, cement bound, unbound materials and also cohesive soils are discussed against the background of current knowledge. Some results from recent research projects on bituminous materials and soils are briefly presented. The importance of reproducing in situ stress conditions in laboratory tests is emphasised and present test methods are critically reviewed. Some of the more important areas for future research are outlined as a result of this review of the current state of the art. The most important of these is considered to be correlation of laboratory determined results and performance in the road, so that the results of laboratory materials testing can be used with confidence in design. /AUTHOR/