The blistering and cracking of the bituminous surfacing of four pavements in Zimbabwe are described and compared with similar damage in South Africa. In all cases the damage was caused by the accumulation of acid sulphate salts below the surfacing due to the use of economically available mining or industrial waste in the base or subbase. Evidence is presesented of production of salt within the subbase and seleted subgrade layers due to further oxidation in situ and of the migration of this salt to the surfacing. A new method of deriving salt limits for lower layers is suggested and used to derive a llimit for a local material. The salts causing the damage include pickeringite, hexahydrite, jarosite, copiapite, rozenite, and probably paracoquimbite and chalcanthite. Some of these have not been previously identified from salt-damaged pavements. Methods of prevention and repair of salt damage are suggested and it is believed that these very economic materials can give trouble-free performance provided certain precautions are taken. (Author)

Media Info

  • Features: References; Tables;
  • Pagination: p. 311-319

Subject/Index Terms

Filing Info

  • Accession Number: 00396699
  • Record Type: Publication
  • Report/Paper Numbers: RR 392
  • Files: TRIS, ATRI
  • Created Date: Aug 25 2004 2:37AM