Characterization of a Road Asphalt by Chromatographic Techniques (GPC and HPLC)

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Abstract
There has long been a need to fractionate asphalt into as well-defined entities as possible. It is known that asphalt consists of a mixture of a very great number of components, too numerous and complex to isolate in the chemically pure state, in appreciable quantities. Consequently, attention has begun to turn towards fractionation of this binder into generic groups, the recombination of which, in varying proportions, should permit experimental evaluation of the influence of a particular fraction on one or another technological property (susceptibility, hardness, etc.) (1). It is also understood that the chemical structures of these generic groups, and their relative proportions, have a fundamental effect on the colloidal structure of asphalt (2, 3), a colloidal structure responsible for rheological behavior (4, 5). Molecular weight distribution has been shown to be a parameter of prime importance (6). It is, therefore, of interest to compare two modern fractionatoin techniques – gel permeation chromatography (GPC), and high performance liquid chromatography (HPLC) – and to characterize, by means of the latter, the fractions of bitumen isolated by the former. Only the key experimental results are given in this paper. Their interpretation, aimed at a deeper knowledge of the physico-chemical structure of asphalts in connection with their colloidal structure and their rheological behaviour, will no doubt require further long experiments with other samples of different origin.