ABSTRACT

Performance-based mix design methods should allow, from the materials properties of the mix and the performance prediction models, estimations of the development of pavement distresses expected over a selected service life, for any pavement structure, in any traffic and environmental condition. The efficiency of these new performance-based mix design methods has still to be proven. However, they represent the basis of the future mix design system. The new mix design methods are no longer based on the criterion of seeking the

optimum mix composition to guarantee maximum value mechanical properties, but rather on that of ensuring definite minimum performance levels. Examples of this concept are presented by the American SHRP Superpave level 2 and 3 and SHRP-A698 methods, the Great Britain approach from Nottingham University and the French approach, the Australian NARC guide level 2 and 3, the Finnish ASTO/Asphalt Specifications, and the Dutch CROW guideline. These mix design methods (SHRP, ASTO, NARC) contain distinct levels. With more

tests, and more time to complete the mix design process, higher reliability of the design is expected. This distinction permits the selection of a design process that is appropriate for the traffic loads and volumes expected for a given paving project so as to design for optimal service and economic performance, rather than maximum achievable performance.