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Title Evaluation of Corrosion Prevention Systems of Strands for PSC Structures
Authors 윤인석(In-Seok Yoon) ; 강현구(Thomas H. K. Kang) ; 신형엽(Hyeong-Yeop Shin)
Page pp.557-565
ISSN 1229-5515
Keywords 강연선 부식; 그라우팅; 그리스; HDPE 도막; 부식 전류밀도 strand corrosion; grouting; grease; HDPE; corrosion current density
Abstract Corrosion of prestressing tendons is closely related to the safety and durability of prestressed concrete. Because PSC strands under large tension stress are vulnerable to corrosion, choice of corrosion prevention systems is quite important. The current study investigated electrochemical estimation and metal loss reduction rate so that the most effective system to prevent steel corrosion can be decided. The types of test specimens are as follows: (a) bare strand, (b) standard cementitious grouting, (c) grease, (d) double protection of grease and grouting, (e) double protection of HDPE sheath after coating with grease, and (f) triple protection of HDPE sheath after double protection of standard cementitious grouting and coating with grease. Acceleration experiments were divided into two types: those with only chloride solution, and those with chloride solution with dissolved oxygen. As for the experimental results, the HDPE sheath had an excellent anti-corrosion performance compared to other methods. However, tendon protected by grouting showed a decreasing corrosion current density with elapsed time, while tendon protected by grease showed a rising trend. In particular, the grease showed poor corrosion protective performance under chloride solution and dissolved oxygen. This was in part due to physical damage of the grease coating by oxygen bubbles. Finally, corrosion was initiated at corrosion current density of 0.15 μA/cm2 under chloride solution, and at 0.17 μA/cm2 under chloride solution and dissolved oxygen.