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Saturday, June 2 • 2:30pm - 3:00pm
(Architecture) Electro-migrating process with silicone quaternary ammonium salt for protecting historic reinforced concrete buildings

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Today, the historic concrete structures from the late 19th and early 20th century are facing severe degradation problems due to chloride ions, carbonation and other aggressive environmental factors. Although repair and reinforcement become urgent, effective methods are still under development. Electrochemical techniques (for example, realkalisation and electrochemical chloride extraction) and corrosion inhibitors have been used in protecting reinforced concrete buildings from corrosion. Recently, bidirectional electro-migrating (BIEM) is considered as a new technique, transferring corrosion inhibitors to the surface of steel rebar to prevent its corrosion. The materials acting as electro-migrating corrosion inhibitors are required to form cationic species in alkalinity concrete pore solution and with high mobility in concrete mortar. The available electro-migrating corrosion inhibitors now normally contain an amine, amino alcohol group or quaternary ammonium salt. But none of them can improve the durability of cement and concrete matrix directly. This study investigated the protective effectiveness of a new electro-migrating corrosion inhibitor--silicone quaternary ammonium salt (Octadecyldimethyl[3-(trimethoxysilyl)propyl] ammonium). Due to its molecular structure, it can create cations in solution and the silane group forms silicic acid by hydrolysis reaction generating silicon-oxygen bonds, which brings consolidating effect; besides the alkyl groups provide hydrophobicity. Experiments were performed in specimens that imitate reinforced concrete. The effectiveness of preventing corrosion was characterized by electrochemical measurements including potential dynamic polarization curve (PD) and electrochemical impedance spectroscopy (EIS) before and after BIEM treatment. The contents of nitrogen in different depth was measured to evaluate the efficiency of migration. Hydrophobicity was evaluated by contact angle after immersion of silicone quaternary ammonium salt. The results showed that the corrosion current (the corrosion kinetic parameters derived from the Tafel plots value) for steel in concrete before and after BIEM treatment was found to be reduced respectively. Improvement of the polarization resistance and charge-transfer resistance were determined by fitting parameters for specimens of EIS, suggesting that the resistance of concrete matrix and steel rebar were both increased after BIEM. The contents of nitrogen becoming higher as the depth increasing, means that silicone quaternary ammonium salt accumulated around the steel rebar. The contact angle was around 90 degree after immersion of silicone quaternary ammonium salt solution. The results obtained in the laboratory experiments indicate that BIEM treatment with silicone quaternary ammonium salt enhance the resistance ability to corrosion of steel rebar. In addition, this material has good migrating mobility in cement paste though BIEM and can maintain hydrophobicity. The investigated results reveal that BIEM technique with silicone quaternary ammonium salt could be a potential multifunctional treatment applied in conservation of historic reinforced concrete buildings.

Speakers
avatar for Shen Ling

Shen Ling

Student, Zhejiang University
Education: PhD student in Department of Cultural Heritage and Museology, School of Humanities, Zhejiang University since September 2017. Supervisor is Hui Zhang, associate professor in Department of Cultural Heritage and Museology, School of Humanities, Zhejiang University March... Read More →

Co-Authors
KC

Kaihao Chen

Bachelor student, Department of Applied Chemistry, University of Electronic Science and Technology of China
July 2017 Graduate from Department of Applied Chemistry, University of Electronic Science and Technology of China Mainly research about how corrosion hibitor that can used in electrochemical treatment affect the characteristics of concrete matrix though labrotory tsets. And the research... Read More →
WC

Wendong Chen

Bachelor student, Zhejiang University
July 2017 Graduate from Department of Chemistry, Zhejiang University, Hangzhou, China. Mainly research about new corrosion inhibitors that can used in protecting historic RC buildings though labrotory tset by electrochemical measurements. Supervisor is Hui Zhang, associate professor... Read More →
HZ

Hui Zhang

Associate professor, Department of Applied Chemistry, University of Electronic Science and Technology of China
Associate Professor,Department of Applied Chemistry, University of Electronic Science and Technology of China, Chengdu, China. Mainly reasch about organic chemical synthesis

Saturday June 2, 2018 2:30pm - 3:00pm
Texas Ballroom C Marriott Marquis Houston

Attendees (20)