Recent literature studies have demonstrated depletion in natural resources; therefore, making resources needed for the pavement industry is more costly. There is a need to minimize cost and to try to reduce the depletion of natural resources. While the recycling of asphalt shingles is beneficial in reducing the consumption of virgin materials, pavement performance should not be compromised. One major concern with recycled asphalt shingles (RAS) relates to the variability in the properties of the recycled materials originating from different sources. In addition, the rheological properties of RAS have not been evaluated as well as its influence on the virgin binder when used in asphalt mixtures. Therefore, the objectives of this study were to characterize the rheological properties and molecular fractions of RAS materials sampled from different sources around the country. In addition, the influence of RAS on the Superpave Performance Grade (PG) of the binder was investigated. Results of the experimental program indicated that the asphalt cement (AC) content in tear-off shingles was consistent among different RAS sources across the country. However, AC content in manufacturer waste shingles was noticeably lower than in tear-off shingles. Furthermore, all extracted RAS binders were graded as PG 118 or higher using the Superpave binder specification system but the low temperature grade was not measurable due to the high stiffness of the binder. This stiff behavior is due to the binder used in shingle manufacturing, which is an air-blown asphalt binder with stiff characteristics and low elongation properties. Results showed that at a RAS content of up to 5%, the high temperature grade of the blends was increased by one to seven grades and the low temperature grade was increased by one grade. The use of binder blending charts is recommended to account for the influence of RAS in the mix design. At a RAS content of 10%,
the binder blends did not pass the Superpave criterion at low temperature.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-04152013-150934 |
| Date | 14 May 2013 |
| Creators | Lodge, Aaron |
| Contributors | Hassan, Marwa, Mohammad, Louay, Okeil, Ayman |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-04152013-150934/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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