Sulphur and ethylene/vinyl acetate co-polymer (EVA) additives have been shown to enhance the properties of rolled asphalt wearing courses; this report describes an investigation into the effect of these additives on the properties of rolled asphalt and dense bitumen macadam basecourse and roadbase materials. Both additives improve the resistance to permanent deformation of basecourses and roadbases. The stiffness modulus is changed in a different way by the two additives, sulphur increasing the stiffness over the temperature range whereas EVA increases the stiffness at high temperatures and reduces it at low temperatures. The additives did not have a serious detrimental effect on any properties and the only limitation was maintaining the temperature of materials below 150 degrees c when sulphur was used. The improvements in the properties of basecourse and roadbase materials resulting from the use of additives has significant implications in the design of road pavements. (Author/publisher)
Abstract