Laboratory evaluation of asphalt mixtures with reclaimed asphalt shingle prepared using the wet process
Document Type
Conference Proceeding
Publication Date
1-1-2014
Abstract
The objective of this study is to conduct a laboratory evaluation of asphalt mixtures containing RAS prepared using the newly-developed wet process. In the proposed wet process, RAS material is blended with the binder at high temperature prior to mixing with the aggregates. The proposed wet process offers the potential to better control the Superpave Performance Grade (PG) of the binder blend, to stimulate chemical and physical interactions taking place in the blend between asphalt binder in shingles and virgin asphalt binder in the mix, and to reduce maintenance issues at the plant due to the high content of fines and fibers in RAS. To achieve this objective, asphalt binder blends were prepared using the wet process and an asphalt mixture with a nominal maximum aggregate size (NMASJ of 12.5mm was designed according to the Superpave design protocol. The mechanistic properties of asphalt mixtures containing RAS materials were evaluated as compared to conventional asphalt mixtures. Laboratory testing evaluated the rutting performance, fracture performance, and low temperature resistance of the produced mixtures using the Hamburg Loaded-Wheel Tester (LWT), the Semi-Circular Bending (SCB) test, and the Thermal Stress Restrained Specimen Test (TSRST). Based on the results of the experimental program, it was determined that the use of RAS through the wet process allows the reduction of the virgin binder content with no adverse effects on the laboratory performance of the mixture as compared to the conventional mixture with no RAS. Results also indicated that the blending of RAS directly with its regular processed size at the recycling plant with no additional processing in the wet process is feasible with no foreseen adverse effects on the mixture performance. However, it is recommended that the RAS be processed to the finest processing size possible at the recycling facility to stimulate chemical and physical interaction between recycled and virgin materials. Based on these results, additional work is needed to simulate plant operations using the newly-developed wet process. Further, research is needed on the shingle asphalt binder availability factor and its variation for the dry and wet recycling processes.
Publication Source (Journal or Book title)
Asphalt Paving Technology: Association of Asphalt Paving Technologists-Proceedings of the Technical Sessions
First Page
197
Last Page
223
Recommended Citation
Alvergue, A., Elseifi, M., Mohammad, L., & Cooper, S. (2014). Laboratory evaluation of asphalt mixtures with reclaimed asphalt shingle prepared using the wet process. Asphalt Paving Technology: Association of Asphalt Paving Technologists-Proceedings of the Technical Sessions, 83 (January), 197-223. https://doi.org/10.1080/14680629.2014.927410