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Influence of accidental over-polarisation on the mechanical properties of cathodically protected pre-tensioned tendons
Materials and Corrosion ( IF 1.6 ) Pub Date : 2020-12-22 , DOI: 10.1002/maco.202012194
Fin O'Flaherty 1 , Ibrahim R. Elomari 1 , Paul Lambert 1, 2
Affiliation  

This paper investigates the performance of pre-tensioned tendons deliberately exposed to higher than normal impressed current cathodic protection (ICCP) to replicate accidental over-polarisation. Plain ungalvanised tendons, 5.4 mm Ø, were pre-stressed in moulds and cast in mortar. Two levels of pre-tensioning were investigated, low (~30% ultimate tensile strength [UTS]) and high level (~80% UTS). Three different degrees of corrosion with target losses of cross-sectional area of 0%–1%, 2%–4% and 4%–7%, respectively, were employed to replicate in situ conditions. ICCP was applied to the tendons at two levels of polarisation, normal protection (ICCP-N) in the range of −650 to −750 mV and overprotection (ICCP-O) ranging between −850 and −1300 mV, both versus Ag/AgCI/0.5-M KCI for an extended period. After ICCP, the tendons were removed from the mortar and slow strain tensile tests were conducted. The results show that ICCP at both normal and overprotection had no significant influence on the elastic modulus, yield, 0.2% proof stress and ultimate strength of the tested tendons. Although ductility was reduced, fracture occurred after reaching the ultimate strength.

中文翻译:

意外过极化对阴极保护预应力筋力学性能的影响

本文研究了故意暴露于高于正常外加电流阴极保护 (ICCP) 以复制意外过极化的预张筋的性能。普通的未镀锌钢筋,直径为 5.4 毫米,在模具中预应力并用砂浆浇铸。研究了两种水平的预紧力,低(~30% 极限拉伸强度 [UTS])和高水平(~80% UTS)。三种不同程度的腐蚀,截面积的目标损失分别为 0%–1%、2%–4% 和 4%–7%,被用来复制原位条件。ICCP 在两个极化水平下应用于肌腱,正常保护 (ICCP-N) 在 -650 到 -750 mV 范围内,过度保护 (ICCP-O) 在 -850 到 -1300 mV 范围内,均与 Ag/AgCI /0.5-M KCI 延长时间。ICCP之后,从砂浆中取出钢筋并进行慢应变拉伸试验。结果表明,ICCP在正常保护和过度保护下对受试筋的弹性模量、屈服强度、0.2%屈服强度和极限强度均无显着影响。虽然延展性降低,但在达到极限强度后发生断裂。
更新日期:2020-12-22
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