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Owing to the large viscosity and mixing temperature of crumb rubber modified asphalt (CRMA), possesses high construction costs, the addition of warm-mix agent can reduce the viscosity and mixing temperature of CRMA. In this study, the Sasobit or DWMA-1 warm-mix agent was added into CRMA to prepare the warm-mix crumb rubber modified asphalt (WRMA). Rotational viscosity (RV) measurement revealed that viscosity of WRMA reduced significantly with the increasing temperature. Dynamic shear rheometer (DSR) showed that Sasobit and DWMA-1 have similar effects on the viscoelasticity of WRMA at the actual pavement temperature (64 °C). Phase separation test showed that the addition of warm-mix agent enlarged the softening point difference, and DWMA-1 had better anti-segregation effect than Sasobit. Fourier transform infrared spectroscopy (FTIR) analyses revealed that there was a chemical reaction after mixing the warm-mix agent and produced new functional groups at 1368 cm−1∼735 cm−1. Fluorescence microscope (FM) and polarizing microscope (PM) analyses indicated that warm-mix agents could improve the solubility between rubber and asphalt. DWMA-1 had a lesser impact on the surface roughness of WRMA compared to another warm-mix agent or composite agent. In addition, preparation method and viscosity reduction mechanism of WRMA was elaborated. This study could be of potential interest for engineering applications of WRMA.
Zhu et al. (Thu,) studied this question.