The viscosity-reducing mechanism of organic wax additive on CRMA

Abstract

CRMA was prepared by mixing PG 64-22 asphalt with crumb rubber powder of 40 mesh size and 18% by weight of the asphalt. Sasobit®, a typical organic wax additive, was selected and added into CRMA. A series of tests, namely, brookfield viscosity, environmental scanning electron microscope(ESEM), component test, differential scanning calorimeter(DSC), fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) were conducted on CRMA with and without organic wax additive, and microcosmic appearance, component content and molecular structure of various asphalt binders were obtained. The test results indicate that the addition of Sasobit® into CRMA can effectively change the contents of components: the content of asphaltenes increases relatively, while saturates decreases. In addition, the interaction between various components of CRMA is weakened, and the state of equilibrium between the dispersant and dispersed phase is changed at the same time. That is why the viscosity decreases after the organic wax additive is added into CRMA.

Keywords

crumb rubber modified asphalt (CRMA) / viscosity-reducing / organic wax additives / mechanism

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