Observation of the development of skid resistance of asphalt wearing courses

Acceptance and warranty requirements for skid resistance have been laid down in Germany in the technical guidelines as a binding component of the contract since 2001. The skid resistance is measured using a side force machine SKM (modified SCRIM) 4-8 weeks after handing over for traffic and at the end of the warranty period, usually 4 years. The requirement values vary dependent on the measuring speed, which is laid down as 80, 60 or 40km/h. The background of experience for the manufacture of skid resistant surfaces is limited at this point in time in the main to wearing courses made from asphalt concrete. As the skid resistance is substantially influenced by the surface texture, it was feared that it will not be possible to adhere to the requirements for wearing courses with a high chipping and low mortar content such as stone mastic asphalt. The known prediction tests were either not yet perfected or not sufficiently correlated with the skid resistance measuring procedure when the skid resistance requirement was introduced. For this reason skid resistance measurements have been carried out on various wearing course types over a long period of time at various distances using the SKM. For the covering abstract see ITRD E157233