Emphasis has been placed on improving resistance to permanent deformation to meet the demand for better surfacing materials for very heavily trafficked roads. Of the materials investigated so far, a copolymer of ethylene and vinyl acetate (EVA) was found to be the most effective and simplest to use. Binders containing EVA also improved the dynamic stiffness of rolled asphalt without adversely affecting laboratory fatigue behaviour. Workability during mixing and laying was also improved. Measurements of the effects of EVA and other polymers, such as epoxy resins and elastomers, on the structural properties of rolled asphalt, and the correlation of some these properties with those of the binder, have also provided a basis for assessing the potential benefits of using these polymers in other types of bituminous material