Impact of non-recyclable plastics on asphalt binders and mixtures

Authors: ALHADIDI, YUSRA - University Of Illinois; AL-QADI, IMAD - University Of Illinois; ALI, UTHMAN - University Of Illinois; MAINIERI, JAVIER - University Of Illinois; Sharma, Brajendra - Bk

Submitted to: Transportation Research Record: Journal of the Transportation Research Board
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2024
Publication Date: 5/9/2024
Citation: Alhadidi, Y.I., Al-Qadi, I.L., Ali, U.M., Mainieri, J.J., Sharma, B.K. 2024. Impact of non-recyclable plastics on asphalt binders and mixtures.Transportation Research Record: Journal of the Transportation Research Board. https://doi.org/10.1177/03611981241245692.
DOI: https://doi.org/10.1177/03611981241245692

Interpretive Summary: A large amount of post-consumer plastic along with agricultural plastic ends up in the environment and stays in there for a very long time. This study evaluated the use of waste plastics as an asphalt binder additive to enhance the performance of asphalt concrete. Performance evaluations of asphalt binder and asphalt concrete were conducted by incorporating two types of waste plastics - low-density polyethylene and polystyrene through dry and wet processes. Overall, it was found that waste plastic did help in reducing the rutting potential, however, the potential for cracking and moisture damage susceptibility varied depending on the mix design and process used. This information can help identify suitable waste agricultural plastics for incorporation into asphalt concrete thereby reducing the amount of agricultural plastic sent to landfills.

Technical Abstract: Low-density polyethylene (LDPE) and polystyrene (PS) were evaluated for incorporation as binder additives for potentially enhancing asphalt concrete (AC) mixture performance. Incorporation of LDPE and PS into asphalt binder resulted in increasing complex moduli over a range of temperatures and frequencies when tested in a Frequency sweep (FS) test and Linear Amplitude sweep (LAS) test. Asphalt concrete performance tests were conducted, including Hamburg wheel-tracking Test (HWTT) to assess potential rutting, Illinois Flexibility Index Test (I-FIT) to determine cracking potential, and indirect-tensile test (IDT) to evaluate moisture susceptibility. Two control mixes, with aggregates from different sources, were designed. For each mix, aggregate blend and binder content were kept constant; and only binder type was changed. LDPE and PS were added through wet process in one mix. Dry and wet processes were used in the other mix. Waste-plastic-modified AC mixes, in both wet and dry processes, exhibited reduced rutting potential and moisture susceptibility. Waste plastics had no effect on AC dynamic modulus, and effect on potential for cracking varied. Results were compared to SBS-modified AC mixes. Waste-plastic provided improvement over control, but less than double-pump styrene-butadiene-styrene (SBS)-modified mix.