Thin layer chromatography performed in stages to identify the presence of aromatic like fraction in chosen bitumen modifiers

Abstract

The organic modifiers are used to alter the rheology of the binder in the asphalt concrete at an added cost. For quality control purpose, recognizing if such material is present in the final blend is of an interest. The thin layer chromatography (TLC) using a flame photometric detector (FPD), in addition to the typical flame ionization detector, was demonstrated hereby as a potential analytical tool for this problem, differentiating between tall crude oil based anti-aging agent, polymer, oxidized bitumen and gilsonite. Gilsonite and anti-aging agent consists of the material soluble in solvent used in the development of the fraction referred to as aromatics. Due to the hindered mobility of modifier molecules on the stationary phase, the elution of aromatic fraction stops at position convoluted with polars I and polars II fraction regions, colloquially referred to as resins and asphaltenes. However, for the color of this fraction within gilsonite is different. The presence of gilsonite is thus identifiable visually after the second development bath, but also to an extent with FPD from the final chromatogram. The thin layer chromatography-flame ionization detectors (TLC-FID) procedure is suggested to be supplemented by infrared spectroscopy to discriminate between non-bituminous and bituminous modifiers of similar response during fractionation.

Keywords

• Road engineering
• Thin layer chromatography
• Flame photometric detector
• Gilsonite
• FT-IR
• SARA