UV/VIS absorption spectra of a few bitumens and their main generic fractions obtained by liquid chromatography have been recorded. Major or minor differences have been found depending on the nature of the bitumen and the generic fraction considered. Those differences are a valuable help in interpreting measurements of binder-aggregate affinity. A spectrophotometry technique has been tried in order to assess this affinity from a physicochemical point of view. It is baaed on the adsorption equilibria in solution between the bitumen or one of its generic fractions and a ‘and’ grading fraction of the aggregate. Both the asphaltenes of the bitumen and the nature of the aggregate play a considerable part in binder-aggregate interactions. The influence of the nature of the aggregate depends mainly on the specific surface of the ‘sand’ fraction used in the tests: with a 0.15 to 0.4 mm fraction this specific surface may vary by a factor up to more than 10, according to the nature of the original aggregate. Orientation tests to obtain more information about the generic fractions have been positive. The asphaltenes can be separated into cyclic-like and resin-like asphaltenes and the resins can be divided into resins with an ‘acid’ or ‘basic’ behaviour