Effect of Construction Joint Preparation on Corrosion of Reinforcing Bars Under Atmospheric Environment

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Title: Effect of Construction Joint Preparation on Corrosion of Reinforcing Bars Under Atmospheric Environment

Author(s): T. U. Mohammed and H. Hamada

Publication: Special Publication

Volume: 212

Issue:

Appears on pages(s): 259-278

Keywords: joints and carbonation; macro-cell corrosion; micro-cell corrosion

Date: 6/1/2003

Abstract:
A detailed investigation on corrosion of steel bars in concrete at construction joints with different joint preparation was carried out. For this cylindrical specimens with joint at the mid-height were made and exposed to the atmospheric environment for 25 years. After 25 years of exposure, the specimens were tested for carbonation depth, and electro-chemical and physical evaluation of corrosion on the steel bars at the joint region. The results conclude that to enhance long-term durability, laitance from the sur- face of the joints is necessary to he removed. After brushing-off the laitance, the application of a mortar coating is found to he very effective for long-term durability. Latex past coating also shows better performance than epoxy. The application of an epoxy coating without brushing-off the laitance shows the worst performance. The application of epoxy after brushing-off the laitance shows the strongest bond strength, it did not, however, show good performance against carbonation and corrosion of steel bars at the joint. Generally, the joint plane is carbonated and carbonation front moves along the steel bars. The cases without treatment for the laitance show a higher carbonation depth along the steel bars through the joint. Corroded area at these joints was also higher.