Materials Performance

NOV 2017

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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62 NOVEMBER 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 11 Corrosion Inhibitor Protects Bridge's Post-Tensioning Tendons e St. Croix Crossing Bridge, a $646 million project that connects Oak Park Heights, Minnesota and St. Joseph, Wisconsin in the United States, uses an innovative extra- dosed superstructure design that combines prestressed concrete box girders and cable stays. To protect the post-tensioning (PT) tendons during construction, a corrosion inhibitor was used. Cable stays support the bridge at five pier locations in the river, while ~1,000 precast boxlike segments are connected by PT tendons that were tensioned and grouted in place. PT cables were also used in the crossbeams connecting upstream and downstream towers at each of the five pier sites. An unseen but important part of con- struction was protecting the PT tendons from corrosion before grouting. Grouting is commonly delayed several weeks or months on long-term proj- ects or when ex- tremely cold winter temperatures inter- rupt continuous grouting. State and federal requirements typically call for cor- rosion inhibitor ap- plication if the wait- ing period is two weeks or longer. To allow segment erec- tion to proceed through the winter months, tendon grouting was able to be postponed in the winter months with the use of a corrosion inhibitor until sub- strate temperatures were high enough that freezing of freshly placed grout was no longer a concern. To protect various post-tension strands placed throughout the bridge during construction, the Lunda/Ames Joint St. Croix Crossing Bridge. Photo courtesy of Minnesota Department of Transportation. CHEMICAL TREATMENT ESSENTIALS Keep your career active by keeping your certification current. By making sure that your certification does not lapse, you will maintain your hard-earned credentials and continue to set yourself apart from the competition. You can also avoid a reinstatement fee or possible suspension of your certification, which could a ffect your current and future jobs. Upon renewal your certification will bear the same value and will continue to represent your professional achievement of certification with NACE. Certi fications are eligible for renewal beginning 90 days prior to the expiration date. An active certification equals an active career! Visit naceinstitute.org/recertify to renew your certification today!

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