Effect of Working Temperature on Rheological Properties of Crumb Rubber Modified Binders With Warm Mix Additives

Abstract

Despite the extensive use of rolling thin film oven (RTFO) for short-term aging of asphalt binders, there is a concern in understanding the rheology of short-term aging characteristics of the crumb rubber modified asphalt binders. Crumb rubber modified binder (CRMB) mixed with warm mix asphalt (WMA) additives Sasobit (S) and Rediset (R) to investigate their short-term aging temperature based on equiviscous principle, i.e., the temperature corresponding to 0.17±0.02 Pa.s viscosity. This temperature is implemented during RTFO aging process to investigate its effect on rutting performance parameters. Rheological tests such as frequency sweep test, temperature sweep test, time- temperature superposition (TTS), high-temperature performance grading (PG grading), and multiple stress creep recovery (MSCR) are studied to understand the influence of RTFO aging temperature on CRMB. The same RTFO aged samples were subjected to pressure aging vessel (PAV) to investigate the fatigue performance parameters using intermediate performance grading, linear amplitude sweep (LAS), thixotropic behaviour. The Fourier transform infrared (FT-IR) spectroscopy and field emission scanning electron microscopy (FE-SEM) are also applied to justify the effects of the WMA additives on the CRM binders in terms of chemically and morphological properties on an RTFO and PAV aged conditions. Finally, the storage stability of CRMB was investigated using a separation tube test. The high-temperature rheological properties revealed that due to an increase in RTFO aging temperature, the critical thermo-rheological behaviour of CRMB in the presence of WMA additives is significantly affected. It was found that CRMB with sasobit additives greatly enhanced visco-elastic properties at 177°C RTFO aging conditions than rediset additives. However, fatigue performance properties indicated that CRMB with rediset additives experienced lower viscosity behaviour at intermediate pavement temperature than sasobit for 177°C RTFO aged followed by PAV aging conditions. Moreover, FE-SEM and FT-IR analysis proved that asphaltene formation was directly dependent on the aging conditions, which helps conserve the rheological properties of base binder present in the CRMB. Finally, storage stability showed a significant phase vii separation in CRMB binder in the presence of WMA due to aging temperature expect stored at 177°C.