Long term aging study of WMA binder
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Warm mix asphalt (WMA) is an environmental friendly technology that contributes to the workers safety, reduction of energy consumption and emissions. In this study, the rheological properties of a PG 64-22 asphalt binder blended with Cecabase RT, Rediset, Evotherm, and Sasobit WMA additives are investigated as a function of laboratory aging. Binders modified with WMA additives and the control samples were both aged in the rolling thin film oven (RTFO) at 143°C and at 163°C, respectively. All samples were then long-term aged in an environmental chamber kept at 60°C. The longterm aged samples were collected at different intervals during a six-month period. Rheological data were collected on each aged sample by performing dynamic shear rheometer (DSR) frequency sweep from 25 to 0.1 Hz. at three different temperatures, i.e. 45°C, 60°C, and 76°C. Samples were also evaluated with the Bending Beam Rheometer (BBR) and Fourier-Transform Infrared (FTIR) Spectroscopy. Gauss-Newton method was vii used for non-linear parameter estimation for modeling the relationship of complex modulus (G*) with temperature, frequency, and aging. Regression analysis was also used for modeling BBR creep stiffness and BBR m-value. Although FTIR results show higher oxidation levels for control than all WMA samples, DSR and BBR results show that Sasobit tends to behave closely to control while Cecabase, Evotherm, and Rediset exhibit lower stiffness than both.