Qualitative Detection of the Presence of Gilsonite in the Bituminous Blends Based on Thin Layer Chromatography

Abstract

The natural asphalts, of which Gilsonite is a representative, are modifiers used to increase the stiffness modulus of the asphalt concrete. For quality control purpose, recognizing if such material is present in the final blend is of an interest. The thin layer chromatography using a flame photometric detector (FPD), in addition to the typical flame ionization detector, was demonstrated hereby as a viable analytical tool for this problem. Gilsonite also contains the material soluble in solvent used in the development of the fraction referred to as aromatics. However, for straight run bitumen and Gilsonite the color of that fraction is different as well as their mobility. Due to the lower mobility of Gilsonite molecules on the stationary phase, the elution stops at different position than for fresh bitumen, convoluting the signal in the chromatogram region typically assigned for resins. The presence of Gilsonite is identifiable visually after the second development bath, but also with FPD from the final chromatogram.