Asphalt Mastic Characterization by Means of Chromatography

ABSTRACT Concentrated solutions of asphalts in cyclohexane were separated into non-polar and polar organic fractions by percolation through beds of pulverized aggregates (<200 mesh) mixed with a filter aid. The polar organic fractions were desorbed from the aggregate using a polar solvent. After drying, the polar organic fractions were weighed. Infrared spectra showed that polar functional groups are concentrated in polar organic fractions. Weights of polar organic fractions from eight asphalts separated on seven aggregates varied by a factor of seven. For a given aggregate, asphalts with the highest asphaltene contents yielded the most polar organic fractions, and vice-versa. Two aggregates consistently adsorb substantial quantities of polar organic fractions from the asphalts, and two other aggregates consistently adsorb relatively small amounts of polar organic materials. This rudimentary method should be capable of refinement and speedup. It might be of use in evaluating interactions of asphalts and mineral fines in mastics. In asphalt-aggregate combinations that exhibit comparatively little interaction (as evidenced by adsorption of small amounts of polar organic materials) in mastics, it is unlikely that interactions will be stronger with larger sizes of aggregates. In other cases, too much adsorption of polar organic materials in mastics might adversely affect pavement properties.