Isolation and characterization of paraffinic components from Venezuelan asphalts. Effects of paraffin dopants on rheological properties of some asphalts

Paraffinic concentrates were isolated from a couple of Venezuelan asphalts, one paraffinic in nature and the other naphteno-aromatic. Multigram scale isolation required two steps. The first one was the separation of neutral hydrocarbons by means of soxhlet extractors filled with clay and extracted with hot cyclohexane. The second step comprised the cryogenic wax crystallization and filtration from neutral hydrocarbons diluted in methyl ethyl ketone, brought to -10 degrees C. Typical operations comprised 800g of asphalt and recovery of 20g of waxes. Separated fractions were characterized in terms of hydrocarbon group-types (SARA) and molecular mass distribution by high temperature size exclusion chromatography (SEC). Remarkable differences were found among the studied asphalts. Doping experiences with the paraffinic concentrates permitted to ascertain differences in the frequency-temperature sweeps, markedly depending on the concentrate origin and to a lesser extent on the amount added. Aromatics coprecipitated with the wax, were observed to be beneficial for asphalt properties.