THE DESIGN OF AGGREGATE GRADINGS FOR ASPHALT BASECOURSES

In a paper at the previous Association of Asphalt Paving Technologists meeting (1984), Brown and Cooper reported on a major testing program of asphalt base and basecourse mixes. The work concentrated on investigating resistance to permanent deformation, while recognizing that it is necessary to optimize mixes to as to also achieve adequate levels of elastic stiffness and fatigue cracking resistance. It was shown that significant improvements to predicted overall mix performance in the road could be achieved by relatively modest changes to current British Standard Specifications. With regard to permanent deformation, however, it was apparent that major improvements could only be achieved by careful design of the aggregate grading. This paper describes the continuing work on this topic.