ABSTRACT
ABSTRACT: The viscoelastic and viscoplastic properties of asphalt binder are valuable to the performance research on the asphalt mixture and pavements. Especially at high-temperature condition, the viscoplastic characteristics of binder play an important role in rutting-resistant performance. This paper presents a viscoplastic modeling method, which originates from the strain-hardening model, to study the unrecoverable strain response for binder in a repeated shear creep recovery test using a Dynamic Shear Rheometer (DSR). Two types of asphalt binders were evaluated in this study, namely the neat binder PG58-28 and the SBS polymer-modified binder PG70-28. In order to fit the model coefficients, a series of 10 cycles repeated creep recovery test were designed to conduct under multiple stress levels 25 Pa, 50 Pa, 100 Pa, doubled to 6400 Pa and three different time durations which included 0.1 s creep + 0.9 s recovery and 1 s + 9 s as well as 10 s + 90 s. Test results and modeling work indicate that, compared with the measured viscoplastic strain, the strain-hardening viscoplastic model can work well on the binder unrecoverable strain response prediction in repeated creep recovery test under lower stress levels and shorter creep duration and it is necessary to take the damage factor into consideration in the future work.
