THE DESIGN AND PERFORMANCE OF HIGH FRICTION DENSE ASPHALTS

The basic microtextural and macrotextural requirements of road/airfield surfacings for skid resistance are described and quantified. It is shown that whereas it is important to produce and maintain the desired microtextural features over the whole vehicle speed range, the requirements for macrotexture are different over different portions of the speed range. These concepts of the most desirable microtexture and the most appropriate macrotexture have been combined into a rational method of aggregate grading design, in order to develop a range of road surfacing materials with good skid resistance properties over the range of traffic speeds and other hydraulic conditions for which they are designed. While the achievement of a safe value of wet skidding resistance is the prime objective of the reported research the aim has been to include, together with these desirable properties of skid resistance, equally necessary properties of resistance to deformation in wheel traks, durability and low noise generation. Results are presented concerning some of the approximately 100 sites so far surfaced with wearing course materials designed according to these principles in order to show their generally satisfactory nature. /Author/