Since about 1969, new types of mixing plants employing simultaneous heating, drying and coating of the aggregate have been introduced in Europe and the USA. Because the moisture in the aggregate is immediately replaced by bituminous binder, these plants are often called 'dustless' or 'drum mixers'; it is claimed that they offer several other advantages over conventional mixers. The author describes the operation of the European Wibau-SL, and the Coatmaster DFE plants, also the American McConnaughay and Shearer processes. Materials produced by these drum mixers are not greatly different from those produced by conventional plants. Results show that there is probably less hardening of the binder in drum mixers because water vapour from the wet aggregate provides a relatively inert atmosphere for mixing. The moisture content of the coated material is usually about 1 or 2 percent. The reduction of dust emission is an important advantage of the drum mixer process/ although it is not completely dustless the small amount of particulate matter and fumes evolved can be more readily and economically removed. Because of their greater simplicity, the initial cost of these plants is less, and savings in the amount of fuel oil used have been reported from the USA. Present specifications, developed around conventional plants, can only be modified when more results of the use of drum mixers are published. /TRRL/

  • Corporate Authors:

    IPC Building and Contract Journals Limited

    Surrey House, 1 Throwley Way
    Sutton, Surrey SM1 4QQ,   England 
  • Authors:
    • Peattle, K R
  • Publication Date: 1975-11

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00133762
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Aug 23 1976 12:00AM