Effect of optimized short-term aging temperature on rheological properties of rubberized binders containing warm mix additives

Abstract

This study investigates the effect of warm mix asphalt (WMA) additives and base binder, on the rheological properties of crumb rubber modified binder (CRMB-55) at higher temperatures. The rheological properties of the base binder VG-30, VG-40, and CRMB-55 are subjected to optimized short-term aging and compared with its unaged condition. WMA such as Sasobit and Rediset additives enhance the CRM binders by optimizing the mixing temperature by reducing it to 18 °C through the rotational viscometer (RV) test. This optimized temperature is implemented on the RTFO aging temperature at 177 °C and compared with both standard mixing temperature of 163 °C for the base binder and 195 °C for the crumb rubber modified binder to simulate the ideal mixing viscosity and to determine its rheological properties. In this study, the dynamic shear rheometer (DSR) is employed to measure the complex shear modulus (G*) and the phase angle (δ) of all the binders at various short-term aging temperatures. The Fourier transform infrared spectroscopy (FTIR) and the Scanning Electron Microscopy (SEM) are also applied to justify the effects of the WMA additives on the CRM binders in terms of chemically and morphological properties. It is identified that the two WMA additives can improve the rheological properties of the CRM binders more effectively by optimizing the short-term aging temperature, and greatly enhance the viscoelastic properties at the high-temperature condition for the CRM binders. It is found that Sasobit has the most remarkable effect on G* and δ at 177 °C RTFO-aged for CRMB-55 than with the Rediset WMA additives, and always suggest implementing this optimized short-term aging temperature for CRM binders before evaluating any rheological behaviour. © 2020 Elsevier Ltd