The nature of coal tars and their variation in composition arises from differences in the rank and type of coal carbonised, and the pyrolisis conditions used. Conventional tars from gas work and coke oven, sources are contrasted with low-temperature tars produced by static, fluidised, or entrained-bed techniques. Characterization of road tars and pitches is discussed with reference to viscosity of road tar and the softening point of pitch. The use of these materials in road construction is summarized. The main advantages of tar over bitumen are better adhesion to stone, greater skid resistance, and better resistance to fuels and mineral oils. Tar, however, has the disadvantage of higher temperature susceptibility. Tar-bitumen mixtures are useful in improving adhesion, anti-stripping properties and skid resistance of bitumen, and in lowering the temperature susceptibility of road tar. Pitch-bitumen mixtures could improve the skid-resistance of hot-rolled asphalt. Tar-polymer mixtures exhibit properties superior to those of tar. Natural and synthetic rubbers have been blended into road tars. Addition of polyvinyl chloride has proved useful for special purposes. Good performance has been noted in low-volatile tars which are manufactured by raising the ratio of anthracene oil II to anthracene oil I from 0.7 to between 1.3 and 3.0. The use of tar for paving is foreseen to increase as the supply of petroleum dwindles. Conventional coke oven tar will be a major source, and tars from various low-temperature carbonization processes and "formed-coke" manufacture will be important alternative sources.

  • Supplemental Notes:
    • Conference on the Efficient Use of Bitumens, Asphalts and Tars as Paving and Construction Materials, Sydney, Australia, 2-3 December 1974; Session 5.
  • Corporate Authors:

    University of New South Wales

    School of Civil Engineering, Anzac Parade
    Kensington, New South Wales  Australia  2033
  • Authors:
    • Maher, T P
  • Publication Date: 1974-12

Media Info

  • Features: References;
  • Pagination: 13 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00095561
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 29 1975 12:00AM