ABSTRACT
ABSTRACT: This paper contributes to the development of a test method for the determination of a binder indicator for the rutting susceptibility of asphalt. Low shear viscosity, measured in oscillation mode in DSR, has been shown to correlate well with the permanent deformation of asphalt, in laboratory tests like the wheel tracking test and the cyclic triaxial compression tests. The task group of CEN TC336 WG1/TG1, responsible for the high temperature binder test methods, developed a new test procedure, published in document prCEN/TS_15324. The procedure leads to the determination of a temperature, at which the viscosity measured at very low shear rate is 2000 Pa.s (EVT: equiviscous temperature). The provisional document prCEN/TS_15324 provides the users with a common test procedure, to collect more data and experience with the method, before actually proposing it as a European standard test method. In this paper, this test procedure was used to measure the EVT of a series of 12 binders (pure bitumen, different types of PmBs, semi-blown bitumen and waxy bitumen). Recommendations on possible improvements of the test are given, which is another step forward towards a European standard test that satisfies the general need for a reliable binder indicator for rutting. Correlations with asphalt tests on mixes prepared with these binders were evaluated and compared to other indicators for rutting. This allowed to evaluate the equiviscous temperature as an indicator for rutting and to investigate whether this indicator actually improves the correlations with permanent deformation tests on asphalt.
