Investigation of the mechanical properties of road surfacing aggregates and particularly of the polishing characteristics has occupied many researchers in recent years. The influence of geological factors on these properties has however not received the same prominence in the literature as the engineering aspects. This paper has been written with a view to gathering together the salient features of the less publicised work.
After reviewing the general requirements of road surfaces the term “roadstone durability” is introduced in the context of surfacing aggregates and the various geological factors likely to influence the roadstone durability are indicated. The influence of petrography upon the strength and the resistance to stripping, abrasion and polishing of roadstones is described together with methods used to assess their potential performance.
Shortage of high quality surfacing materials has resulted in the development of artificial aggregates and some aspects of this work are described.