A new Polish standard for road bitumens has been prepared respecting European Standard proposal given by CEN TC 19. Penetration grades of road bitumens have been chosen for Polish conditions. Considering the chosen penetration ranges and assumptions of penetration index range from -1 to +1 and S-type of bitumen according to Heukelom, the optimum rheological properties zones for each grade have been calculated. The calculations have given optimum ranges of: Fraass Breaking Point, Softening Point, dynamic viscosity at 60 degrees C and at 135 degrees C. These optimum ranges have been compared with proposed respective CEN TC 19 proposals for Fraass Breaking Point and Softening Point (viscosity requirements have been given by CEN TC 19 by now). The proposed requirements have been compared with measured properties of Polish bitumen samples taken systematically in 1993 (85 samples) and of bitumen samples of four different foreign producers (11 samples). CEN TC 19 requirements proposal shows good agreement with respective optimum rheological properties zones. Measured properties of most of the samples have met proposed requirements, with exception of a group of bitumen samples of Fraass Breaking Point exceeding the required values. The applied calculation method allowed to established requirements for bitumen grades viscosity at 60 degrees C. This requirement has also been found critical for some bitumen samples. The new penetration grades replacing existing Polishstandard classification might have an important influence on road pavements service performance. The most influential will be splitting of D70 grade (Pen25 = 65-85 dmm) onto two grades D50/70 and D70/100. Relationship of viscosity at 60 degrees C and penetration at 25 degrees C has shown nonlinearity with a sharp change of slop in the range of penetration at 25 degrees C 60 dmm. Decrease of penetration below this limit results in a much greater increase in viscosity at 60 degrees C than above this limit. New grades of road bitumens will cause a significant increase in pavement rutting resistance. (A).
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