01661616

Component

The inclusion of recycled asphalt shingles (RAS) in asphalt mixtures has become increasingly common, but design principles vary significantly by agency. The primary objectives of this paper included evaluating the binder availability concept for RAS mixtures through a carefully design laboratory experiment, demonstrating a balanced mixture performance testing approach for the design of RAS mixtures, and evaluating field data of RAS mixtures placed in the Midwest. Three asphalt mixture designs were evaluated with RAS contents of 0.0, 2.5% and 5.0%, and produced to contain equivalent mixture volumetrics. The available RAS binder availability factor was determined to be approximately 100%. In addition, performance tests including the Hamburg wheel tracking performance test and disk-shaped compact tension test were conducted to characterize high and low temperature mixture performance. The addition of RAS improved rutting resistance, as expected. DC(T) fracture results demonstrated that a soft base binder effectively permitted the design of a thermal crack resistant RAS mixtures. Field investigations demonstrated similar performance of pavement surfaces containing RAS to those containing only RAP or virgin materials. The study also demonstrated a balanced mix design approach, which is being adopted by several agencies in the Midwest. This appears to provide mix designers and agencies with a reliable approach for designing innovative asphalt mixtures with higher recycling levels and heterogeneous composition in general. This appears to be a simpler, more mixture-centric alternative to the primary method suggested in AASHTO PP78-17, which entails arbitrary VMA bumping plus binder extraction, recovery, and advanced binder testing.

This paper was sponsored by TRB committee AFK30 Standing Committee on Non-Binder Components of Asphalt Mixtures.

18-05496

English

5p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

Figures; References; Tables

Asphalt mixtures; Binders; Mix design; Performance measurement; Recycled materials; Shingles

Highways; Materials; Pavements

Transportation Research Board Annual Meeting 2018 Paper #18-05496

TRIS, TRB, ATRI

Jan 8 2018 11:24AM