Polering av asfaltbeläggning

Torbjörn Jacobson

In many countries, where studded tyres are prohibited, the traffic polishing of the coarse aggregate in the wearing courses is a problem to a rather great extent. In those countries there are often regulations on the aggregate polishing value. In Sweden, where the use of studded tyres is extensive, the micro texture of the aggregate in the surface of the wearing courses increases during the winter season. Therefore, there have been few problems with low wet friction levels in Sweden. However, the increased use of wear resistant aggregates and stone mastic asphalt together with lightweight studs has led to a reduced amount of wear. During later years, a problem with low friction levels has been noticed in wear resistant surface courses during late summer and fall, especially at high trafficked roads with a complicated geometry. Measurements have shown that the friction level can be reduced rather quickly on surfaces with aggregates that are disposed for polishing and low wet friction related accidents have been reported. This report is a knowledge survey covering polishing, friction and to some extent surface texture and wear caused by studded tyres. Experiences from friction measurements mainly in Stockholm and Gothenburg have been compiled in this report. A review of testing methods and existing requirements is also presented in the report. Friction measurements have been carried out with two friction measurement equipments, SAAB Friction Tester and BV12, where the measuring speed, time of the year, the amount of water film thickness, the type of tyre and tyre pressure have been varied.



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