The development of a method for the design of hot-mix asphalt istraced. The design of gradations based on aggregate packing characteristics was found to be impractical for routine mix design. Measurement of elastic stiffness and assessment of resistance to permanent deformation was made possible with the development of the nottinghamasphalt mix tester. This development provided a method of designingmixes using relevant mechanical properties as design criteria. The percentage refusal density equipment was used to manufacture specimens at levels of compaction that should be achieved in practice. For a particular source of aggregate, the effect of binder content and aggregate gradation on volumetric composition and mechanical properties can be assessed. Certain volumetric and test criteria are appliedto identify the mix or mixes that will perform satisfactorily. The final mix formulation can then be selected on the basis of certain practical and economic considerations. This paper appears in transportation research record no. 1317, Asphalt mixtures: design, testing, and evaluation 1991.
Abstract