A CONTRIBUTION TO THE STUDY OF STRUCTURAL STATES OF BITUMENS

CONTRIBUTION A L'ETUDE DES ETATS STRUCTURAUX DES BITUMES

The authors tackle the problem of the colloidal structure of bitumens on the basis of work undertaken by American and Soviet research workers, whose ideas are set forth and discussed. The model adopted assigns a very specific role to asphaltenes and is based on the simulation of the behaviour of real bitumens through systems in which maltheenes are replaced by tetralin. The bitumen is thus considered as a pseudo-binary system whose two basic constituents are asphaltenes and malthenes. This leads to a thermodynamic approach which can be represented by a phase diagram in composition-temperature coordinates. This diagram is sketched starting from the principle of superposition of domains of structural states and domains of rheological behaviour which are accessible experimentally. By viscosity measurements of mixtures of asphaltenes and malthenes or tetralin in variable proportions and at different temperatures, the transition is revealed between single phase sol systems, whose behaviour is Newtonian, and two-phase sol-gel systems, whose behaviour is viscoelastic. Reasoning leads to the pediction of the existence of another single phase domain, with high asphaltene concentrations, corresponding to the gel system. An original method of studying the rheological behaviour of viscoelastic systems, based on the analysis of the relaxation of a cylindrical sample, is proposed. It use an apparatus designed for the purpose. The exploitation of this experimental procedure, based on analogy with chemical kinetics, leads to proposal that the substances studied be characterized in terms of the order, that is to say of the exponent in the differential equation of the law of relaxation. The systems studied (distillation asphaltenes + tetralin and asphaltenes obtained from air-blown bitumen + tetralin) are of different orders, found to be 2 and 3 respectively. /Authors/

  • Corporate Authors:

    Central Laboratory of Bridges & Highways, France

    75732 Paris,   France 
  • Authors:
    • DRON, R
    • Bestougeff, M
    • Voinovitch, I A
  • Publication Date: 1979-3

Language

  • French

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 51 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00190177
  • Record Type: Publication
  • Source Agency: Central Laboratory of Bridges & Highways, France
  • Report/Paper Numbers: Research Report 75
  • Files: TRIS
  • Created Date: May 26 1979 12:00AM