Effect of Different Additives on the Characteristics of Asphalt Mastics
| Autor: | Kuei-Yi Lin, 林桂儀 |
|---|---|
| Rok vydání: | 2006 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 This paper investigates the influences of different additives such as fiber, sulfur, recycling agent on the characteristics of asphalt mastics. First, fibers including cellulose, rock wool and polyester types were added to asphalt binder. Then the reinforcement and anti-aging mechanism of bitumen-fiber mastics were evaluated by conducting the scanning electron micrographs, essential physical tests and rheological test. Test results indicate that the reinforcing and anti-aging effects were resulted from the volume-filling, physic-chemical and particle-interaction reactions in turn between fibers and asphalt. In addition, the Kerner model was applied to explain the mechanic behavior of mastic in terms of effective volume of fiber. The optimum fiber content is dependent on fiber type, length and diameter and is found to be 0.3, 0.4, 0.4 and 0.3%by mixture weight for organic, mineral, short polyester and long polyester fibers, respectively. The second part of this paper described the effects of sulfur on the mechanical behavior and storage stability of the polymer-modified asphalt (PMA). The viscosity, microscopy and rheological tests were conducted to characterize the engineering properties of PMA. Without sulfur added, the PMA was microheterogeneous and was made up of two distinct finely interlocked phases, especially at high SBS concentrations. After the addition of sulfur, PMA showed smaller asphalt domains and a fairly homogeneous dispersion of the asphalt in the SBS matrix. The compatibility between polymer and asphalt produced an elastic network into the asphalt. The addition of sulfur resulted in an excellent elastic system and substantially increased the rheological properties of PMA. Because of the colloidal nature of asphalt cements, their engineering properties of asphalt were highly improved for three reasons: (1) the reinforcement of the SBS polymer, (2) the physical-chemical interaction between SBS and asphalt, and (3) the presence of the dispersed phase resulting from sulfur. Therefore, highway agencies as well as contractors will benefit from using storage-stable PMA prepared through sulfur vulcanization. A viscoelastic model which was the combination of Mooney equation and Kerner model was examined and shown to be appropriate to predict the rheological properties of the asphalt-SBS blend mixed with sulfur. This model could help pavement engineers better design the engineering properties of PMA from the individual component. The third part of this paper was to develop models to detect the suitable content of reclaimed asphalt pavements (RAP) according to the binder and mixture properties and to discuss the diffusion process of recycling agent. Results indicated that the Vis-Mix model and Grunberg model are capable to decide the suitable RAP content in the recycled asphalt concrete (RAC) for the AC-10 and recycling agent, respectively. The modified Hirsch model based on the theory of micro-mechanism accurately simulated the rheplogical trend of recycled asphalt binder (RAB) at wide temperature and RAP content ranges. In addition, The Fick’s law is feasible to predict the diffusion coefficients and describes the diffusion effect and process of recycling agent perfectly. Finally, the addition of recycling agent is able to not only restore the characteristics of aged asphalt binder but also increase the allowable amount of RAP. Therefore, it appears that the recycling agent is the other suitable additive as well as AC-10 asphalt for the technology of recycled asphalt concrete. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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