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In the past years a wide discussion has been held among asphalt researchers regarding the existence and interpretation of observed microstructures on bitumen surfaces. To investigate this, the RILEM technical committee on nano bituminous materials 231-NBM has conducted a round robin study combining differential scanning calorimetry (DSC) and Atomic Force Microscopy (AFM). From this, methods for performing DSC and AFM tests on bitumen samples and determination of the influence of wax on the observed phases, taking into account thermal history, sample preparation and annealing procedure, are presented and critically discussed. DSC is used to measure various properties and phenomena that indicate physical changes such as glass transition temperature (T g) and phase transition such as melting and crystallization. In the case of existence of wax, either natural or synthetic, it can further indicate the melting point of wax, that could be used to determine wax content. The results from seven laboratories show

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The original SuperPave asphalt binder specification criterion for fatigue, G* sin δ, has received considerable criticism. Recently, a time sweep using the dynamic shear rheometer (DSR) has been proposed as an alternative test method for developing load-associated fatigue information for asphalt binders. This proposed test method is examined with respect to a phenomenon called edge fracture. Edge fracture is reported in the literature for steady state and oscillatory flow in DSR, but it has not been reported for asphalt binders. The modulus, when plotted versus number of cycles generated in a time sweep test, has the appearance typical of fatigue behavior; however, the actual response of the material depends markedly on the initial modulus of the material. The development of the modulus with repeated shearing is described with respect to flow of the asphalt binder at its circumference. The data are examined with respect to their validity as a measure of fatigue, and recommendations with respect to the use of time sweep data in a binder specification are presented.