Quality checking of Polymer modified bitumens in Slovenia

Abstract

For many years the properties of bitumen have been determined based on mechanical tests as needle penetration, Ring&Ball and Fraass fracture temperature. For elastomer (styrene-butadiene-styrene) polymer modified bitumens these tests are not sufficient to show the important differences in bitumens. Elastic recovery and cohesion provide better insight, but rheological properties cannot be adequately described with conventional test. The requirements of the polymer modified bitumens (PmB) in Europe were defined in EN 14023 in 2010 [1]. Since then several new tests were introduced in the research field and their procedures improved. In the European Standards Committee (CEN) TC 336, there is ongoing work to develop performance related specifications. New laboratory test methods from American standards were adapted and transformed into EN standards (bitumen laboratory aging methods and rheological tests). These test methods are not yet employed in the current PmB European standard, however, the draft prEN 14023, April 2020 [2] suggests these new tests. In the recent years at ZAG Laboratory for asphalts and bitumen-based products long-term aging of bitumen by pressure aging vessel (PAV) and rheological tests were introduced. Traditional bitumen test methods are performed together with new rheological tests e.g. Dynamic Shear Rheometer (DSR) testing, to characterize complex modulus and phase angle, and Multiple Stress Creep Recovery Test (MSCRT) in order to develop a preliminary data base on PmB’s, which are frequently used in Slovenia. The paper presents the current requirements for PmB’s in Slovenia and test results on PmB 45/80-65, original, laboratory aged and extracted from produced asphalt mixtures.