1st World Conference on Highway Surfacing [antikvár]

Dames, Jürgen liivestígatioos on the Effect of diíTerent Mineral Aggregates on the Performance of Ashak Wearing Courses with respect to Skid Resistance Sununary In the course of the construction of the autobahn A70 between Schweinfiirt and Bayreuth, the Bamberg test segment was built in the summer of 199!. A totál of 21 selectively varied asphalt mixes in 200 m iong sub-segments were constructed in both unidirectional roadways. The ajm of the investigations was to demonstrate the importance of the polishing resistance of the mineral aggregates used for the skid resistance development of wearing courses of asphalt concrete and stone mátrix asphalt. Now, after 5 years under traffic, the skid resistance development is assessed on the individual test panels. It is shown that asphalt mixes with a uniform type of rock clearly develop under the action of traffic towards the polishing resistance of the rock and that in the case of the mixing of mineral aggregates of dififerent polishing resistance the greater effect results from the finer partiele sizes and not from the coarse aggregates. 1.Introduction Within the scope of a research project sponsored by the Federal Minister of Transport, the interrelationship between the polishing resistance of aggregate or crushed sand respectively and the skid resistance development of asphalt wearing courses was to be demonstrated by means of the construction of appropriate test panels. In this wav, the question was to be clarified as to whether and how the skid resistance of asphalt with mixes composed of mineral aggregates of dififerent polishing resistance can be affected and thus what importance the individual partiele size groups have in respect to skid resistance development under traffic. Finally, the possibilities of forecasting the skid resistance of laboratory tested asphalt mixes was to be reviewed and likewise examined in the field. 2.The Bamberg Test Segment A totál of 21 test panels each 200 m iong on both unidirectional roadways across the full width were prepared in the summer of 1991 on the autobahn A 70 west of Bamberg in order to impiement these goals Table 1 shows the design of the individual asphalt mixes with respect to type of asphalt, maximum particie size and type of rock. As a generál condition for the quality control test, the volumetric design of the individual mix components, - especially the bitumen content - was agreed to and