RUSTING REINFORCEMENT - THE NO 1 PROBLEM IN CONCRETE DURABILITY

The rusting of reinforcement in concrete is the single most important cause of poor durability of structural concrete. The author describes the chemical reactions of the constituent materials and suggests possible methods to combat the corrosion. The likelihood of metal corrosion depends upon the ph of the material containing the metal and the electrical redox potential of the metal. The poarbaise diagram is used to show the natural corrosion-protective action of portland cement concretes. However, reaction of the hydrated cement paste with atmospheric carbon dioxide reduces the ph of concrete to a value where corrosion of embedded steel is possible, especially in the presence of oxygen and water. The effect of chlorides in the concrete is discussed, and the dangers in using calcium chloride as a set accelerator are illustrated. The weathering of concrete can release chloride ions which can migrate to establish high concentrations. Chloride ions can be electrolytically removed from contaminated highway structures. Possible solutions to the problem of reinforcement corrosion discussed include the use of a modified steel and the cladding of the steel with another metal or an electrically insulating material. Perhaps the best protection is to ensure that the concrete is of the best quality and adequate thickness. (TRRL)

  • Availability:
  • Corporate Authors:

    Cement and Concrete Association

    Wexham Spring
    Slough SL3 6PL, Buckinghamshire,   England 
  • Authors:
    • FIGG, J W
  • Publication Date: 1980-5

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 34-36
  • Serial:
    • CONCRETE
    • Volume: 14
    • Issue Number: 5
    • Publisher: THE CONCRETE SOCIETY
    • ISSN: 0010-5317

Subject/Index Terms

Filing Info

  • Accession Number: 00323109
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: May 21 1981 12:00AM