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Open AccessArticle

Study on the Effect of Microwave Processing on Asphalt-Rubber

1
School of Highway, Chang’an University, Xi’an 710064, China
2
Chongqing Municipal Research Institute of Design, Chongqing 400000, China
*
Author to whom correspondence should be addressed.
Materials 2020, 13(2), 411; https://doi.org/10.3390/ma13020411
Received: 19 December 2019 / Revised: 6 January 2020 / Accepted: 9 January 2020 / Published: 15 January 2020
(This article belongs to the Section Construction and Building Materials)
The addition of crumb rubber (CR) into base asphalt plays a critical role in the improvement of the performance of Asphalt-Rubber (AR) binders. However, due to the problems, like high constructing temperature and energy consumption brought by the additional rubber, the use of AR binders could be limited in some areas. During this study, CR is processed by microwave is adopted to reduce the viscosity of the AR binders system, while the CR processed by long screw extrusion also is studied. First, the swelling (the absorption of light component into the CR particle) and dissolution (some molecules of CR dissolving into the base asphalt), both of which determine the improved performance of AR binders, are investigated by fluorescence microscopy and extraction tests. The size of the CR particle after swelling observed by fluorescence microscopy is used to evaluate the swelling rate of CR samples, and the ratio of the weight loss of CR samples after extraction to the original weight is employed to measure the dissolution rate. Then, Brookfield rotational viscometer and storage stability tests are conducted. Last, the rheologic performance, including high and low-temperature performances, is characterized by the dynamic shear rheometer (DSR) and bending beam rheometer (BBR), respectively. The fluorescence microscopy and extraction results show that microwave processing could effectively increase the swelling and dissolving rate, with the figures rising twofold and more than threefold, respectively. The results show that microwave processing could effectively reduce the viscosity of AR binders, with a viscosity decrease of 65% at 190 °C and, at the same time, the high temperature of Performance Grade (PG) decrease from 88 °C to 76 °C. The storage stability could be negatively impacted, but it is slight and the low-temperature performance is improved slightly. View Full-Text
Keywords: asphalt-rubber; microwave processing; swelling; dissolution; viscosity; high-temperature performance; low-temperature performance asphalt-rubber; microwave processing; swelling; dissolution; viscosity; high-temperature performance; low-temperature performance
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MDPI and ACS Style

Xu, J.; Li, R.; Liu, T.; Pei, J.; Li, Y.; Luo, Q. Study on the Effect of Microwave Processing on Asphalt-Rubber. Materials 2020, 13, 411.

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