Use of n-propyl bromide solvents for extraction and recovery of asphalt cements

Centrifuge extraction and Rotavapor recovery were used to determine the eff ect of solvent type (trichloroethylene and four n-propyl bromide products) on recovered asphalt binder properties. Mix variables included three binder s mixed with each of two aggregate sources (one gradation). When recovered binder properties were compared to the original binder properties, the tric hloroethylene solvent combined with the extraction and recovery processes o ccasionally produced higher (i.e., stiffer) recovered binders. One n-propyl bromide product appeared to be incompatible with the polymer-modified PG 7 6-22. This incompatibility was seen as a distinct stringy, rubber-like resi due in the extractor. Fourier transform infrared analysis showed that this same product also seemed to inhibit or actually limit normal heat-related c hanges. Overall, the data indicate that n-propyl bromide solvents can be us ed as direct replacements for the chlorinated solvents historically used fo r hot-mix asphalt extraction and binder recovery.