Polymers are added to asphalt binders primarily to stiffen the binder at higher temperatures and thus to protect the pavement against rutting at summertime temperatures early in the pavement's life. Also, it has been noted that polymers typically increase the ductility of a binder and that some polymer-asphalt combinations are especially effective. Furthermore, it is hypothesized that enhancing a binder's ductility, and maintaining this enhancement with binder oxidative aging, contributes to enhanced binder durability in pavements. However, polymer-asphalt interactions and how they might contribute to improved binder performance is not well understood. The goal of this work was to probe the relationship of polymer morphology on asphalt binder rheology and mixture durability. Experiments were conducted on asphalt mixtures and binders, and as a function of oxidative aging. PFC mixtures, which are an open mixture designed to allow enhanced water drainage, were of specific interest. These mixtures were tested for Cantabro Loss, an indicator of a mixture's likelihood of failure by raveling. Asphalt binders were tested using dynamic shear rheometry (DSR), which provided the DSR function, (G' /η'/G'), a measure of binder stiffness that includes both the elastic modulus and the flow viscosity), ductility (used to measure the elongation a binder could withstand before failure), gel permeation chromatography (GPC), used to estimate the relative amount of polymer) and fluorescence microscopy (used to image the polymer morphology in the asphalt binder). From these data, relationships were assessed between binder morphology and binder rheology and between binder rheology and mixture durability, all as a function of binder oxidative aging. Polymer morphology related to ductility enhancement. Polymer morphology related to a change in the DSR function, relative to the amount of polymer, as measured by the polymer GPC peak height. Cantabro loss correlated to the DSR function (R2=0.963). The overall conclusion is that polymer morphology, as indicated by fluorescence microscopy, relates to both the rheological properties of the binder and the Cantabro loss of the mixture. These relationships should yield a better understanding of polymer modification, increased mixture durability (decreased raveling) and improved rheological properties (DSR function and ductility).

This study focuses on the effects of mixing temperature, binder content, and dust content on the performance of Stone Matrix Asphalt (SMA). Mixes produced at different mixing temperatures and with or without added polymer modified binder (Pb) and/or bag house dust (BHD) were evaluated. Two different types of specimens: laboratory mixed laboratory compacted, and plant mixed laboratory compacted were evaluated by Cantabro Mass Loss (CML) testing in an unaged condition or after a laboratory conditioning protocol (CP) was applied. Additional Pb and BHD were added to plant produced mixes in the laboratory before mixing. Results showed that mixing temperature affected behavior in some cases. Specimens with lower air void (Va) levels performed better than those with higher Va levels. Additional polymer modified binder and BHD, when added together, meaningfully improved mixture results in terms of CML values.

Die Arbeit befasst sich mit der Untersuchung des Kernformstofffließens als nichtnewtonsche Fluidströmung. Dazu werden verschiedene Formgrundstoffe und Kernformstoffe rheologisch untersucht. Als Bindersysteme kommen PUR Coldbox und Wasserglas zum Einsatz. Für diese Untersuchungen wird ein eigens für diesen Zweck entwickeltes Messgerät verwendet. Die gewonnenen Daten werden in ein numerisches Modell implementiert, welches mit den Methoden der numerischen Strömungsmechanik den Kernschießvorgang abbildet. Dabei kommt der Open Source CFD Code OpenFOAM zum Einsatz. Der Kernschießvorgang wird mit verschiedenen Kernkastengeometrien numerisch und experimentell untersucht und die Ergebnisse verglichen. Die Ergebnisse der rheologischen Untersuchungen zeigen deutlich den Einfluss der Beschaffenheit des Formgrundstoffes und des Bindersystems auf die Fließfähigkeit des Kernformstoffes. Der Vergleich zwischen Experiment und Simulation zeigt gute Übereinstimmung. Das formulierte Modell gibt die Möglichkeit, Probleme in der Kernqualität vorherzusagen.