Friction and the texture of aggregate particles used in the road surface course

Skid resistance, the road surface’s contribution to friction, is a crucial property of a road surface course required to maintain a safe and serviceable road network. Measurement of skid resistance is restricted by the need to measure the forces acting on a rubber wheel or slider while it is dragged across the surface. If the skid resistance of the road could be determined without the need for contact then measurement could be cheaper and more thorough. One route to achieving this goal is by measurement of the texture of the road that generates the friction experienced by a sliding tyre. However, the form and scale of the texture required is not well defined. The work presented in this thesis attempts to establish a robust methodology for measurement of texture on the surfaces of aggregate particles (the main constituent of the road surface course) so that it can be compared with friction. The stages of development are described in detail and the methodology is employed to examine the changing texture on two types of aggregate. The mechanisms by which these aggregates polish, methods for characterising their surface texture, and the consequences for the friction they are able to generate are explored.EThOS - Electronic Theses Online ServiceGBUnited Kingdo