Chemo-mechanics of epoxy-asphalt

Pavements of enhanced longevity would be expected to withstand long-term traffic as well as varying environmental conditions reducing in this way the major maintenance needs. Considering also the adoption of long-term contracts by road authorities, long-life pavements have started to attract the interest of road contractors worldwide. New and relatively new binders specially designed to produce long-life pavements have been proposed to minimize the regular maintenance and reconstruction operations. Among others, one promising technology to reach this goal is the epoxy modified asphalt binder, or epoxy-asphalt. Nevertheless, the addition of epoxy resins to asphalt binders may result in materials of inferior properties. Thermosetting epoxy resins may not mix homogeneously in asphalt binders leading to immiscible or partially miscible binders, which are mostly phase-separated materials. The phase-separated epoxy-asphalt binders can become brittle and thus more prone to cracking, leading the pavements to fail. Only a few epoxy products are applicable in asphalt binders, and the knowledge of incorporating chemistry to develop miscible epoxy binders remains unknown. For this to be the case, this thesis aims to provide a fundamental approach to elucidate the chemical and physical processes that determine the phase behavior of these binders. A vital role in implementing the thermosetting epoxy-asphalt binders also plays the curing. To obtain fundamental insights into the material curing, multi-physics models and experimental methods are considered in this research to identify and assess the curing-induced changes of epoxy-asphalt. The development of rheological properties that reflect the material workability is determined by laboratory experiments and used as input to multi-physics simulations. As the ultimate scope of implementing the epoxy-asphalt is to increase the longevity of pavements, the oxidation-induced changes of epoxy-asphalt materials as a function of time are evaluated as well in this research to prove their high aging resistance for wearing courses. Within the same framework, emphasis is also given to the effect of epoxy-asphalt on the durability and mechanical performance characteristics of an asphalt concrete mix. In conclusion, this thesis contributes to elucidating the factors that determine the curing- and oxidation-induced changes of epoxy-asphalt and understanding what bears miscible binders. The modeling and experimental programs discussed throughout the thesis can help to provide the fundamental knowledge to design and develop new binders and binding systems of the desired properties and characteristics.