The results observed in experimetnal roads laid in 1967 encouraged further research into the effect on performance of bitumens from different crude sources and having different penetrations. The changes in permeability, voids content and texture depth were also studied. It was found that materials with a high initial permeability can retain spray reducing properties for a considerable time. An unusual result was obtained with 100 pen Venezuelan bitumen which has led to an early compaction of the pervious macadam. This binder is characterized by high miscibility with oil and resistance to weathering. The results are also reported of laying pervious macadam to investigate improved bituminous surfacings for heavily trafficked motorways and to study the occurrence of oily black deposits on motorways. It was found that 20 mm nominal size pervious macadam has a longer effective life under heavy traffic than the 10 mm friction course. Useful spray reduction can be achieved under the heaviest motorway traffic for at least 3 years. Bitumen of lower viscosity than 100 pen should not be used as otherwise the spray-reducing life is shortened. The use of bitumens which show a higher miscibility with oil is liable to lead to early compaction and should be avoided. Comments are made on manufacture and laying, merit ratings and costs compared with other surfacings, noise, and skid resistance.

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: p. 30-40

Subject/Index Terms

Filing Info

  • Accession Number: 00163667
  • Record Type: Publication
  • Report/Paper Numbers: S.C.W. Record 2 Proceeding
  • Files: TRIS
  • Created Date: Mar 14 1978 12:00AM