Corrosion of reinforcing steel and post-tensioned steel in concrete

混凝土中钢筋和后张钢筋的腐蚀

• 批准号: 191868-2010
• 负责人: Hansson, Carolyn
• 金额: $ 2.4万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=546033
• 关键词: Corrosion; reinforcing; steel; post; tensioned

Concrete is strong in compression but readily cracks under tensile loads. In reinforced concrete structures, reinforcing bars limit the width of these cracks; however, the presence of cracks makes the bars susceptible to corrosion. Post-tensioning was invented to combat the weakness of concrete under tension. In addition to minimizing cracking in the concrete, post-tensioning reduces the amount of concrete and steel used compared to the conventional reinforced concrete structures, which is economically and environmentally beneficial. All steel embedded in concrete develops a protective film on the surface similar to that which forms on stainless steel and which protects it from corrosion. Nevertheless, the most common cause of failure of reinforced concrete in Canada is corrosion of the reinforcing steel. This is because chlorides from de-icing salts or marine atmospheres penetrate the concrete through pores and cracks in the cement paste and destroy the protective film on the steel. While there is a large body of research on the penetration of chlorides into sound concrete and the resultant corrosion process, much less is known about the role of cracks in exacerbating these processes and how the post-tensioning system fares when exposed to salts.

混凝土在压缩方面很强，但在拉伸负荷下很容易裂缝。在钢筋混凝土结构中，钢筋限制了这些裂缝的宽度。但是，裂缝的存在使钢筋容易受到腐蚀。发明了张紧后，以应对张力下混凝土的弱点。除了最大程度地减少混凝土中的破裂外，与常规的钢筋混凝土结构相比，在经济和环境上有益于常规的钢筋混凝土结构相比，使用的混凝土和钢的量减少了。 混凝土中嵌入的所有钢都在表面上形成了一种保护性膜，类似于不锈钢上形成的保护膜，并保护其免受腐蚀。然而，加拿大钢筋混凝土失败的最常见原因是加固钢的腐蚀。这是因为从冰盐或海洋大气中的氯化物通过水泥糊中的毛孔和裂缝穿透混凝土，并破坏钢上的保护膜。尽管关于氯化物渗透到声音混凝土和最终的腐蚀过程中有大量研究，但对裂纹在加剧这些过程中的作用以及张紧后系统在暴露于盐时的票价的了解少得多。