Dynamic mechanical testing of bitumen: sample preparation methods Available to Purchase

The dynamic shear rheometer (DSR) is one of the most complex and powerful instruments currently used to characterise the flow properties of bitumen. With the increased rheological characterisation of bitumens, particularly polymer-modified bitumens, by means of these dynamic mechanical methods, there is now an urgent need to standardise DSR testing procedures to ensure the repeatability and reproducibility of the rheological data. This paper describes an investigation of the influence of three sample preparation methods (hot pour, silicone mould and weighing) on the magnitude and repeatability of rheological parameters measured during DSR testing. The effect of the different sample preparation methods has been evaluated for a penetration grade and polymer-modified bitumen using a controlled-stress rheometer. The results indicate that a method involving the pouring of hot bitumen onto one of the plates of the DSR and then trimming the edge of the sample is the most consistent means of sample preparation. In addition, the magnitude of the measured rheological parameters is influenced by the sample preparation method, with the silicone mould and weighing methods producing consistently higher and lower values of complex modulus respectively than the hot-pour method.