|Company||ASI Solutions Ltd|
Surface grip (friction) is a major safety characteristic of an asphalt surface course. Once the bitumen film has been removed from the aggregate by vehicle trafficking, the micro-texture (roughness) of the aggregate is exposed which provides grip with tyre contact. This fine scale micro-texture of the surface aggregate is the main contributor to sliding resistance and is the dominant factor in determining wet skidding resistance at lower speeds.
Macro-texture is important for high speed roads to aid the rapid drainage of surface water from the tyre and pavement interface thereby reducing the risk of aquaplaning. The texture depth is a measure of the macro-texture and is an important factor influencing skidding in wet conditions on high speed (>65km/h) roads.
The micro-texture characteristics of aggregates depend on its polishing susceptibility under the action of tyre forces. To ensure the pavement surface will provide the appropriate level of grip required, the aggregate used in the surface course should be specified to have a minimum Polished Stone Value (PSV). PSV is a measure of an aggregate’s resistance to polishing under wear, or becoming smooth under traffic. The higher the PSV, the more resistant the aggregate is to polishing (becoming smoother).
To view the full RHINODUST case study click here.