01626344

Component

Asphalt-stabilized bases (ASB) can be considered either as a “high-quality base” or a “low-quality hot mix asphalt (HMA).” The design process based on high-quality base philosophy employs the use of asphalt content-density curve to estimate the optimum asphalt content (OAC) of the mix. In the low-quality HMA design philosophy, the estimation of the OAC relies on satisfying the volumetric properties of the mix. Both approaches also usually require a minimum mix strength. Since it is impractical to change the gradation of the ASB mixes, due to economic reasons, it is often difficult to satisfy all the volumetric requirements of HMA design. The ASB design process for the determination of the OAC is further varied when considering possible design impacts from differing laboratory compactors (Texas Gyratory Compactor vs. Superpave Gyratory Compactor), applied number of gyrations, and the presence of recycled materials. In this study, a process for obtaining the optimum asphalt content of ASB is recommended with principles following that of high-quality base design philosophy. A laboratory study was performed on four diverse materials. The mix designs based on low-quality HMA typically yielded slightly higher asphalt contents (about 4.5%) when compared to the mix design based on high-quality base (about 3.7%). Within each design philosophy, the OAC is shown to be independent of the gyratory compactor and the applied number of gyrations (75 and 100 gyrations). The addition of 3% recycled asphalt shingles (RAS) to the mixes resulted in 10% to 25% increase in the indirect tensile strength (IDT).

This paper was sponsored by TRB committee AFS80 Standing Committee on Stabilization of Geomaterials and Recycled Materials. Alternate title: Determining Optimum Asphalt Content of Asphalt Stabilized Base.

01618707

17-06765

English

12p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Asphalt content; Mix design; Optimization; Recycled materials; Shingles

Asphalt stabilized base; Indirect tensile strength

Design; Highways; Pavements

Transportation Research Board Annual Meeting 2017 Paper #17-06765

TRIS, TRB, ATRI

Dec 8 2016 12:47PM