Quantifying physical and rheological properties of trichloroethylene-asphalt system to improve performance evaluation of recycled asphalt

Abstract

In extracting the aged asphalt from field pavement via centrifugal extraction method, the trichloroethylene solvent tends to reside in the recycled asphalt, which can bias the property assessments of the recycled asphalt. This research evaluated the physical and rheological properties of the recycled asphalt that contained different masses of trichloroethylene, via fluorescence microscopy, Fourier transform infrared (FTIR) and dynamic shear rheology tests. Based on the test results, the effects of trichloroethylene on the properties of asphalt-trichloroethylene system were derived. It was found that the fluorescence microscope worked well for distinguishing the morphologies of trichloroethylene and asphalt in the trichloroethylene-asphalt system. A method was thus developed based on microscope image recognition to calculate the content of trichloroethylene in the asphalt. The FTIR results indicated that the interactions between the trichloroethylene and asphalt compositions generated two new absorption peaks in the infrared spectra, namely 562 cm−1 and 994 cm−1. The ratio of the above two peak areas (i.e., I994/I562) exhibited a two-stage linear varying trend with the trichloroethylene content, which provided references for predicting the trichloroethylene content in the asphalt using the infrared spectra. Trichloroethylene also influenced the rheological properties of recycled asphalt, including the shear modulus, phase angle, non-recoverable deformation and elastic recovery. As the trichloroethylene content rose, the shear modulus and elastic recovery of the trichloroethylene-asphalt system reduced, while the phase angle and non-recoverable deformation of the system increased. The above relationships between the trichloroethylene content and the properties of the asphalt-trichloroethylene system were expected to exclude the effect of the residual trichloroethylene on the asphalt properties, to improve the performance assessments of the recycled asphalt.