ABSTRACT
The most commonly used procedure for mixture design is based upon the Marshall test, which was originally developed in the USA for designing mixtures for use on airfield runways. Recipe mixtures provide a satisfactory performance in many cases and there is some advantage in the simplified approach that recipe mixtures offer. Porous asphalt is a bituminous material designed to provide a large volume of interconnected air voids so that water can drain through the material and run off within the thickness of the layer. New approaches to bituminous mixture design have been proposed. The Superior Performing Asphalt Pavement mixture design process was developed in the USA through the Strategic Highway Research Program in the early 1990s. Asphalt mixtures on heavily trafficked roads are also subjected to permanent deformation and fatigue tests as part of the mixture design process. An alternative type of mixer is the drum mixer, which gives continuous rather than batch production.
