MOLECULAR INTERACTIONS OF ASPHALT IN THE ASPHALT-AGGREGATE INTERFACE REGION

Evidence for molecular interactions in the asphalt-aggregate interface region was demonstrated by using 3 different approaches: a study of asphalt-aggregate interactions by inverse gas-liquid chromatography (IGLC), chemical analysis of strongly adsorbed species, and physical measurements of molecular adsorption. IGLC studies showed that polar asphalt molecules, initially present or formed on oxidation, interact strongly with aggregate surfaces. Asphalt fractions showed more interaction with limestone than with quartzite. The catalytic effect of a mineral surface on the oxidation of asphalt fractions was shown. Limited IGLC studies also showed a correlation between asphalt-aggregate interactions and water-stripping resistance. Ketones, dicarboxylic anhydrides, and carboxylic acids were found to be the major asphalt components strongly adsorbed to road aggregates; they were concentrated in the strongly adsorbed fraction by factors of 1.9, 9.5, and 14 respectively. Evidence for multilayer adsorption of asphalt molecules on mineral surfaces was obtained by heats of immersion, flow through porous media, and photomicroscopy studies. The results indicated that adsorption, or molecular orientation, of asphalt molecules in the asphalt-aggregate interface region is a slow process and often continues for many hours and even days at 150 C(423 K). The adsorbed layer appears immobile at 150 C (423 K), and its buildup rate, typically of the order of 20 A/min with normal aggregates, is affected by both the nature of the mineral surface and the composition of the asphalt. Speculation about the possible significance of the reported studies to asphalt paving technology is presented.

Media Info

  • Media Type: Print
  • Features: References; Tables;
  • Pagination: pp 67-78
  • Monograph Title: Characteristics of and factors influencing bituminous materials and mixtures
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00095569
  • Record Type: Publication
  • ISBN: 0309023599
  • Report/Paper Numbers: #517
  • Files: TRIS, TRB
  • Created Date: Jul 2 1975 12:00AM