Determination of modifier contents in polymer-modified bitumens and in samples collected from the roads using high-performance gel permeation/size-exclusion chromatography

This paper describes application of high-performance gel permeation/size-exclusion chromatography (GPC/SEC) for the determination of content of polymer modifiers in modified road bitumens. The obtained results were compared with the measurements based on the procedure recommended by the American Association of State Highway and Transportation Officials, which employs Fourier transform mid-infrared spectroscopy. Two most commonly used modifiers of paving bitumens, namely, styrene–butadiene–styrene and styrene–butadiene copolymers as well as modified bitumens sampled from various streets in the city of Gdansk (Poland), were investigated. This work confirmed the ability of GPC/SEC to distinguish modified road bitumens from unmodified ones. The developed methodology is particularly important in quality control of modified bitumens, as well as in arbitration analysis when there is a suspicion that the amount of modifier added to bitumen was lowered or that the material does not meet the specifications concerning the modifier content.