Volume 29, Issue 5 (September 2001)
Use of n-Propyl Bromide Solvents for Extraction and Recovery of Asphalt Cements
Centrifuge extraction and Rotavapor recovery were used to determine the effect of solvent type (trichloroethylene and four n-propyl bromide products) on recovered asphalt binder properties. Mix variables included three binders mixed with each of two aggregate sources (one gradation). When recovered binder properties were compared to the original binder properties, the trichloroethylene solvent combined with the extraction and recovery processes occasionally produced higher (i.e., stiffer) recovered binders. One n-propyl bromide product appeared to be incompatible with the polymer-modified PG76-22. This incompatibility was seen as a distinct stringy, rubber like residue in the extractor. Fourier transform infrared analysis showed that this same product also seemed to inhibit or actually limit normal hear-related changes. Overall, the data indicate that n-propyl bromide solvents can be used as direct replacements for the chlorinated solvents historically used for hot-mix asphalt extraction and binder recovery.