MnROAD Cells 16-23 (Phase II): Forensic Investigation into Recycled Unbound Base and Asphalt Surface Materials

Status:  Complete
Report Date:  08/17/2017


This report presents the findings from eight years of performance evaluation of eight Cells (Cell 16-23) built at MnROAD in 2008. The constructed cells addressed two studies: 1) performance evaluation of an unbound base materials (i.e., recycled asphalt pavement, recycled concrete aggregates, and taconite) and Class-5 as road base materials and 2) performance evaluation of surface materials that incorporate warm mix additives, recycled asphalt pavement, and different PG binders. The eight Cells were tested utilizing surface distress survey, rutting, FWD, IRI, and Friction. The DCT test was performed on the mixture samples, and the performance of unbound base materials (Cell 16-19) was evaluated with LWD, DCP, and gradation test. After eight years of service (approximately 5.6 million ESAL), the Cells were in good condition relative to surface distress, rutting, stiffness, IRI, and friction. Consequently, it was difficult to compare the performance difference between various unbound materials and mixtures. Unbound recycled material and taconite performed as well as Class 5 in terms of gradation, DCP, and LWD. All mixture types, regardless of RAP contents, binder grade, and the presence of WM additive, exhibited similar performance. Finally, correlation between DCT fracture energy and thermal low-temperature performance of mixtures could not be found due to limited number of cracks on the Cells.

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