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Laboratory Investigation of the Performance of Fiber-Modified Asphalt Mixes in Cold Regions
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- Author / Creator
- Perca Callomamani, Luis Alberto
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An efficient and safe road network is of great importance for a country, not only to ensure its competitiveness and productivity in the global trade market but also to connect its territory internally. Thus, increasing the lifespan of asphalt concrete roads and the enhancement of the mechanical properties of asphalt mixes are desired targets among transportation ministries. There are traditional ways to achieve this aim, for instance, modification of asphalt with polymers is a common way to enhance the mechanical properties of the binder. Meanwhile, fibers with high-mechanical performance represent an important case to evaluate in terms of their effectiveness to improve asphalt concrete properties.Improvement of the mechanical properties of asphalt mixtures allows them to be more resilient to rapid deterioration, in particular, distresses such as thermal cracking. Thermal cracking is caused by contraction of asphalt layers at low temperatures: under these conditions, tensile stresses build up to a critical point, where crack formation starts. The cracks then propagate under traffic loading conditions. In cold regions, freeze-thaw cycles accelerate crack propagation within the asphalt. Later, this deterioration in the asphalt layer may lead to the formation of more severe distresses such as potholes. Furthermore, other distresses may appear simultaneously within the asphalt layer, including rutting failure at warm temperatures and fatigue failure at intermediate temperatures. Fibers have attracted increasing attention within the asphalt industry due to their potential use as asphalt concrete modifiers. The addition of fibers within of Hot Mix Asphalt (HMA) could result in a composite material that has higher tensile strength, along with the ability to absorb greater energy during the fracture process. The fiber–aggregate–asphalt cement interlock acts as a crack barrier, preventing the formation and especially the propagation of cracks in the asphalt mix. Besides these effects, fibers may also increase the fatigue life of hot mix asphalt (HMA) and provide resistance to permanent deformation.This research focuses on the evaluation of the effectiveness of the addition of polymeric fibers to HMA to increase resistance to cracking at intermediate and low temperatures, and rutting resistance and moisture susceptibility at high temperatures, and evaluation of the effect of the addition of polymer fibers on fatigue failure of HMA. For this purpose, three different types of polymeric fibers, including uncoated aramid (Aromatic polyamide), polyethylene terephthalate (PET), and polyacrylonitrile (PAN), were added to conventional hot asphalt mixes. The resulting samples were compacted, and the mechanical properties of the fiber-modified HMA were compared to conventional HMA samples in the laboratory. Based on the results obtained, the addition of fiber showed, in most cases, a consistent trend compared to conventional HMA samples. This included improvements in rutting control, cracking resistance, and fatigue life. Finally, a material cost comparison was conducted for use as a reliable source of information when selecting materials to employ as a cost-effective solution, while fulfilling minimum industry specifications.
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- Graduation date
- Spring 2020
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.