This paper presents the results of a study into wear of heavily-trafficked pavement on winding road in Auvergne, France. The wearing course was bituminous concrete with high stone content and rolled-in chippings. During monitoring, the macrotexture was little changed but skid resistance fell in difficult road layout, showing that pavement geometry plays an important part in maintaining skid resistance, and wearing course grading design and the characteristics of the aggregates have a significant effect. Seven very thin bituminous concretes of differing composition were tested over the road section. After one year under traffic, differences showed between grading in the sample sections. After two years the mechanical strength of the aggregates was affected more than their polishing resistance. On the basis of initial findings, two designs were shown as useful for this type of road. The paper includes a section discussing aggregates for road use. These need anti-skid characteristics, must be contained within the pavement structure, and must retain their integral properties. The ideal rock would consist of hard and soft minerals in equal proportions. Specifications for inherent aggregate characteristics pose problems for recent gap-graded bitumen techniques in use of difficult sites.
Samenvatting