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Post-Tensioning Corrosion Evaluation and Mitigation


Corrosion of post-tensioned tendons can lead to wire/tendon break and possible bridge collapse is a serious problem for bridge owners. Water bleeding and grout segregation from portland cement grout and improper grout installation have created pockets of voids and water/moisture in many bridges. Water or sufficient moisture presence and/or corrosive ion concentration has caused corrosion in the tendons. Formulated, prepackaged grout has been an important advancement, however, soft grout pockets have been found , resulting in significant tendon corrosion in many bridges. PT corrosion evaluation (CE) correlating the moisture level to the corrosion condition of the tendon, tendon drying to remove water/moisture and injecting corrosion-resistant materials has been employed in unbonded post-tensioned structure for more than twenty years. These technologies have successfully mitigated tendon corrosion and reduced the wire/strand breakage rate significantly. These technologies are finding their way into applications in post-tensioned bridges. CE helps to evaluate corrosion environments and corrosion risks of the post-tensioned tendons, and tendon drying and corrosion-inhibiting material impregnation can improve the environment for the tendon and mitigate corrosion. Embedded zinc sacrificial anodes have been included in patch repairs of steel reinforced concrete structural elements as well was prestressed concrete bridge suffering from corrosion since the mid-nineties. Unlike impressed current cathodic protection (ICCP) system which may cause prestressed steel hydrogen embrittlement, sacrificial anodes are safe to use in post-tensioned structures. This poster/paper presents the causes of post-tensioning corrosion and the resulting corrosion damages, then introduces different evaluation techniques and corrosion mitigation systems to improve the durability of the posttensioned bridges. Keywords: post-tension corrosion evaluation, cathodic protection, corrosion, post-tension impregnation, embedded anodes, post-tensioned tendon, and tendon drying.

Conference Paper Details

Session title:
Liao Haixue
David Whitmore