Crumb rubber (CR) is a widely used waste material in asphalt pavement due to its low cost and high elasticity. A broad range of pretreatment methods has been employed to activate CR surface to improve the compatibility between the asphalt materials and CR. However, this was accompanied by increased costs and reduced high-temperature performance of the rubberised asphalt binder. In this study, the outer surface of aggregated CR particles was activated chemically through a series of solution soaking pretreatments. The chemical reactions were detected through the Fourier-Transform Infrared Spectroscopy (FTIR), the surface morphology was verified by a Scanning Electron Microscope (SEM), and the effect of the treatment was investigated by the Dynamic Shear Rheometer (DSR). The results showed that the chemicals used in this study could activate the CR surface. New functional groups such as the carbonyl group bond (C=O) and carbon–nitrogen bond (C-N) were generated, and changes occurred on the C=C stretch peak at 1635 cm−1 and C=C bend peak at 692 cm−1 as the intensity of the peaks increased and decreased, depending on the effect of the solution used. The nitro group intensity was decreased after all pretreatments due to the chemical reactions between the nitro group and the different solutions. The SEM images showed that the mixed solutions (NaOH and KMnO4) had the most significant effect on surface morphology as the CR surface appeared with a large roughness spread over the whole sample. Furthermore, the rutting resistance of the rubberised asphalt binder improved with the decreased index value of the carbonyl and sulfoxide groups of the CR surface. The treatments used in this study improved the surface activation of the CR and enhanced the compatibility of the CR with the asphalt binder.