Laboratory investigation of cup lump modified bitumen emulsion

Abstract

In recent years, bitumen emulsion in cold mix asphalt (CMA) has gained much attention because of its economic and environmental benefits. However, cold mix asphalt faces some major concerns related to its performance. Bitumen modification with polymer is considered to be an effective way to enhance its performance. In the present study, cup lump rubber (CLR) was used as a new modifier for the preparation of new cup lump modified bitumen emulsions (CMBE) to improve its performance. In addition, to further understand the modification mechanism, we discussed the effect of CLR and emulsification on basic engineering properties, chemical composition compatibility, elemental compositions, thermal properties, phase microstructures, surface morphology, and micromechanical features of CMB and its evaporation residues. The results indicate that the basic properties of modified bitumen with CLR were improved, emulsification affects the basic performance to some extent. The inclusion of CLR did not show any significant change in the functional groups of CMB. Moreover, the CLR was dispersed homogeneously and resulted in a stable multi-phase structure of CMB, resulting in satisfactory compatibility. Whereas the emulsification did not affect the elemental composition of evaporation residues of CMB. Furthermore, the thermal stability was enhanced by CLR addition, and the emulsification further improved the thermal properties of all types of bitumen. In addition, the CLR modification and emulsification did not significantly affect the crystalline structure of bitumen and their evaporation residues. Finally, atomic force microscopy results exhibited that the addition of CLR increased the size of bee-structures, which prevented the oxidization of chemical components and enhanced the diffusion ability of bitumen molecules, but the emulsification decreased the size and increased the formation of bee structures, thus improving the physical properties of the evaporation residue of modified bitumen.