Doctor of Philosophy (PhD)
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Seung Jae Lee
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The reuse and recycling of materials, especially materials derived from nature, is necessary for a sustainable environment and world. Asphalt mixture is a combination of asphalt binder and aggregates, both of which originated from nature. The reuse and recycling of aged asphalt materials (RAP) is widespread. However, a large portion of these materials is wasted. One primary reason for the reluctance to use a high percentage of RAP in recycled asphalt is uncertainty in the long-term performance of recycled asphalt pavement. To improve the long-term performance of recycled asphalt, new additives and Recycling Agents (RA) are used to modify the binder’s properties. However, different RAs will change the recycled binder’s properties differently, resulting in different long-term recycled binder properties. Therefore, this study was conducted to correlate the chemical indices and rheological properties of the recycled binder using different recycling agents.
Furthermore, the performance of recycled binders was evaluated to predict the long-term performance of recycled binders according to their unaged and initial properties. The results showed that the chemical indexes (carbonyl and sulfoxide) of recycled binders can be used to predict the long-term performance of recycled binders. These results could also be used to select the proper RA in the recycling of RAP material. Also, an asphalt design procedure based on the chemical indices of binders was developed for use by practitioners and researchers. The previous design method was based on Performance Grade tests, while the developed method is mostly based on the chemical properties of binders, and its tests are easier and more economical.
Furthermore, the incorporation of RAP percentage in the unmodified PG 67-22 binder was limited to 20% by the Florida Department of Transportation due to uncertainty in the long-term performance of recycled asphalt. To increase the percentage of RAP in recycled asphalt, new additives are used to modify the asphalt binder. One of the newly introduced additives is nanoclay particles, which were applied in the recycling of RAP and were investigated in this study. The results showed an increase in the incorporation of RAP percentage in the nanomodified binder by 30% compared to using unmodified (neat) asphalt binder. The improved properties of the nanomodified binder compared to the unmodified binder proved the feasibility of using a nanomodified binder in severe weather conditions and roads that experience higher loads and traffic.
Baqersad, Mohamadtaqi, "Rheological and Chemical Characteristics of Asphalt Binders Recycled using Recycling Agents and Nanoparticles" (2020). FIU Electronic Theses and Dissertations. 4415.
Available for download on Friday, February 26, 2021
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