Evaluation of solvents for asphalt extraction

The laboratory evaluation of the performance of a number of asphalt extraction solvents was conducted. The performance testing was conducted on unmodified and polymer modified asphalt binder with the Bitumen Degradation Test (BDT) and on polymer modified and RAP mixtures with centrifuge extraction. The chemical interaction between the binder and the solvent was analysed by Fourier Transform Infrared (FTIR) Spectrometry. Several commonly used extraction solvents were tested including trichloroethylene, dichloromethane, toluene and xylene along with a number of alternative agents. The alternative agents included chlorinated, petroleum-based and bio-sourced solvents. The chlorinated solvents (trichloroethylene-TCE, dichloromethane and two higher exposure limit candidate agents) were found to be the best solvents to dissolve the binder in the BDT. These solvents were tested in the final round with centrifuge extraction, where they were evaluated based on the ability to dissolve the binder and evaporate after the extraction. While TCE had the best performance, some candidates were found to perform almost as effectively as the trichloroethylene, making them viable alternatives to the latter.