INFLUENCE OF THE CEMENT ON THE CORROSION BEHAVIOR OF STEEL IN CONCRETE

A CONSIDERABLE AMOUNT OF CALCIUM HYDROXIDE IS FORMED DURING THE HYDRATION OF PORTLAND CEMENT, AND MAINTAINS HIGH PH IN CONCRETE. AS A RESULT, A THIN OXIDE FILM IS FORMED OVER REINFORCING STEEL, WHICH THOROUGHLY PROTECTS IT FROM CORROSION UNDER MOST CIRCUMSTANCES. MOREOVER, THE CEMENT PASTE HINDERS DIFFUSION TO THE STEEL OF THE ATMOSPHERIC OXYGEN NEEDED FOR CORROSION. CHLORIDES TEND TO IMPAIR THE PROTECTIVE FILM, BUT 2 PERCENT OF CALCIUM CHLORIDE BY WEIGHT OF CEMENT IS USUALLY NOT SIGNIFICANTLY CORROSIVE IN ORDINARY REINFORCED CONCRETE. CHLORIDES ARE BEST AVOIDED IN CONCRETE IN CONTACT WITH PRESTRESSING WIRES. CORROSION IS ELECTROCHEMICAL IN NATURE. GALVANIC CELL ACTION DEVELOPS, AND DIFFERENCES IN CONCENTRATIONS OF SUBSTANCES IN THE FREE WATER IN CONCRETE LOCALIZE AND INTENSIFY THE CORROSION. /PCA/

• Authors:
  • Steinour, H H
• Publication Date: 0

Media Info

• Serial:
  • Portland Cement Assoc R & D Lab Bull
  • Issue Number: 0

Subject/Index Terms

• TRT Terms: Calcium compounds; Coatings; Corrosion protection; Hydration; Hydroxides; Oxides; Portland cement; Reinforced concrete; Reinforcing steel
• Old TRIS Terms: Oxide coatings
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00213607
• Record Type: Publication
• Source Agency: Portland Cement Association
• Report/Paper Numbers: No 168
• Files: TRIS
• Created Date: Jun 1 1970 12:00AM