It is well known that asphalt rheology affects the cracking performance of asphalt binders. For many years researchers have struggled to develop tests that adequately deal with this aspect of pavement performance in a manner that can be incorporated rapidly into a specification. The use of the fatigue parameter developed during the Strategic Highway Research Program (SHRP), G*sin δ, has been shown to be a poor surrogate for cracking performance. Other tests, such as the direct tension test, used for cold-temperature cracking, also have been implemented poorly into specifications. However, use of the bending beam rheometer as an indicator of cold-temperature cracking has been widely adopted. As a result, a pavement stiffness of 300 MPa has been regarded as a reasonable parameter for cold-temperature cracking performance. The interrelationship between cold-temperature cracking parameters and those selected for fatigue cracking is not well understood. The onset of brittle behavior that occurs around 300 MPa stiffness and the selection of a fatigue parameter G*sin δ at 5 MPa are not wildly divergent in concept. More recently, the Glover–Rowe parameter has been revealed as a good indicator of cracking performance. In this paper we explore those differences that have occurred and make suggestions for the use of alternate parameters to better define the rheology of the binder as it relates to cracking.

No abstract

The flow behavior of commercially available, aseptically packaged vanilla pudding was measured using a Thermo Haake RheoStress rheometer (RS1, Thermo Electron Corporation, Waltham, MA) with a concentric cylinder system. Six different shear rates, ranging from 1 to 100/s, and three reasonable serving temperatures were investigated using constant shear rate tests. A time-dependent, Herschel-Bulkley model characterized the thixotropic nature of pudding. The model's five parameters were related to temperature. The model was validated at three constant shear rates and at two different temperatures, and was found to predict viscosity well as a function of time, shear rate and temperature.

Abstract-The production of accurate detector models is of high importance in the development and use of detectors. Initially, MCNP and Geant were developed to specialise in neutral particle models and accelerator models, respectively; there is now a greater overlap of the capabilities of both, and it is therefore useful to produce comparative models to evaluate detector characteristics. In a collaboration between Lancaster University, UK, and Innovative Physics Ltd., UK, models have been developed in both MCNP6 and Geant4 of Cadmium Zinc Telluride (CdZnTe) detectors developed by Innovative Physics Ltd. Herein, a comparison is made of the relative strengths of MCNP6 and Geant4 for modelling neutron flux and secondary γ-ray emission. Given the increasing overlap of the modelling capabilities of MCNP6 and Geant4, it is worthwhile to comment on differences in results for simulations which have similarities in terms of geometries and source configurations.

No abstract