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Recycling 2019, 4(1), 11; https://doi.org/10.3390/recycling4010011

Balancing the Performance and Environmental Concerns of Used Motor Oil as Rejuvenator in Asphalt Mixes

1
Department of Civil, Architectural, and Environmental Engineering, Missouri University of Science & Technology, Rolla, MO 65409, USA
2
Research and Technology at Pure Asphalt Company, Chicago, IL 60526, USA
3
Department of Chemistry, Missouri University of Science & Technology, Rolla, MO 65401, USA
*
Author to whom correspondence should be addressed.
Received: 12 December 2018 / Revised: 19 February 2019 / Accepted: 19 February 2019 / Published: 23 February 2019
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Abstract

Road deterioration inspires researchers to enhance the properties of asphalt binder for better performing mixes. Recycled tire rubber, or crumb rubber modifier (CRM), and used motor oil (UMO) are two modifiers that enhance asphalt binder performance through two different mechanisms. CRM affects high-temperature properties while UMO modifies low-temperature properties. Potential environmental concerns arising from the use of UMO have been raised in the literature. In this paper, the two recycled materials were investigated for their ability to complement each other. Both performance benefits of using both materials and the environmental concerns of using UMO were studied. Four CRM asphalt binders were investigated: two with UMO and two without UMO. Environmental impacts were evaluated using gas chromatography to check air emissions for benzene, toluene, ethyl-benzene, and xylenes (BTEX). The potential for toxic leaching of elements from modified hot mix asphalt (HMA) were checked using the US Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Protocol (TCLP). For asphalt binders modified by CRM-UMO combinations, CRM decreased the amounts of released BTEX components, presumably by absorbing UMO and slowing the release of BTEX. Leaching results concluded that UMO mixtures showed a notable percentage of sulfur (S) as compared to non-UMO mixes. All these leachate components were under EPA limits. View Full-Text
Keywords: UMO; modified asphalt; Rejuvenator; CRM; BTEX; TCLP; EPA; MSCR Test; Master curve; Cole-Cole diagram UMO; modified asphalt; Rejuvenator; CRM; BTEX; TCLP; EPA; MSCR Test; Master curve; Cole-Cole diagram
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Deef-Allah, E.; Abdelrahman, M.; Fitch, M.; Ragab, M.; Bose, M.; He, X. Balancing the Performance and Environmental Concerns of Used Motor Oil as Rejuvenator in Asphalt Mixes. Recycling 2019, 4, 11.

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