The properties of paving bitumens in relation to their performance in road surfacings

The deformation and flow behaviour of paving bitumens under sinusoidal loading in simple shear is described in terms of the complex (time dependent) shear modulus and the phase angle. The treatment of such data to separate the effects of temperature and time of straining is indicated. The critical temperature and straining conditions encountered by a bitumen in a pavement surfacing after long term hardening are then considered and the complex modulus and phase angle levels associated with the conditions are identified. Hardening of the bitumen in service is decided by the intrinsic resistance of the material to hardening by oxidation, by the high temperature severity conditions at the site and by the degree of exposure of the bitumen in the surfacing to the atmosphere. The level of hardening at which surfacing distress occurs is related to the low temperature severity conditions at the site. Methods for reducing the rate of hardening of a bitumen in service are then discussed in terms of selection of crude petroleum source, refinery processing and the addition of antioxidants. Hydrated lime is the most promising antioxidant tested to date. This additive might be used at concentrations up to 12 per cent by mass of the lime/ bitumen mixture for spray seal constructions. (This concentration corresponds approximately to an hydrated lime content of 1 per cent in a plant mix composition) (a).

Language

  • English

Media Info

  • Pagination: Jan-23

Subject/Index Terms

Filing Info

  • Accession Number: 01438574
  • Record Type: Publication
  • Source Agency: ARRB
  • ISBN: 869100203
  • Files: ATRI
  • Created Date: Aug 24 2012 9:37PM