Influence of Surface Condition and Loading on the Corrosion Behaviour of Stainless Steel Reinforcing Bars

The current Canadian Highway Bridge Code specifies a 75 year service life for all new highway bridges. Such requirements cannot be met with conventional “black” steel reinforcement because of the high use of chloride-containing de-icing salts, and the most suitable alternative is stainless steel. Although the lifetime costs of structures with stainless rebar are predicted to be significantly lower than with any other materials, the initial costs are often considered to be prohibitively high. The main reason for this is the cost of the alloying elements, chromium, nickel and molybdenum, which are responsible for the corrosion resistance of these alloys. Although these costs have decreased recently, authorities are still seeking reductions in cost. An additional cost, recommended by the alloy suppliers, is imposed by the removal of the mill scale and associated Cr-depleted layer formed during hot rolling of the bar. This is achieved by blasting the mill scale with stainless steel chips and then pickling in a mixture of nitric and hydrofluoric acids. However, mill scale is not removed from black steel and has not been found to have a negative impact on the steel’s performance. Moreover, any Cr-depleted layer is likely to have been replenished by diffusion during the period that chlorides normally take to diffuse through the concrete cover. The main purpose of this investigation was to determine if this blasting and pickling process is necessary for the performance in concrete exposed to chlorides, of three grades of stainless steel, 304LN, 316LN and 2205, from two different suppliers, Valbruna Canada and Carpenter Technology Corporation. To this end, the three steels, in both as-rolled and blasted/pickled conditions, have been tested in synthetic concrete pore solution, embedded in mortar and embedded in concrete.

  • Corporate Authors:

    Ontario Ministry of Transportation

    1201 Wilson Avenue
    Downsview, Ontario  Canada  M3M 1J8
  • Authors:
    • Hansson, CM
    • Anders, KA
    • Bergsma, BP
  • Publication Date: 2009

Language

  • English

Media Info

  • Pagination: 1 v., 60p.

Subject/Index Terms

Filing Info

  • Accession Number: 01149436
  • Record Type: Publication
  • Source Agency: Transportation Association of Canada (TAC)
  • Files: TAC
  • Created Date: Jan 28 2010 7:22AM