Acoustic Nondestructive Testing of Steel Reinforcing Members in Concrete

Many concrete structures contain internal pre- and post-tensioned steel structural members that are subject to fracturing and corrosion. Corrosion of steel components can lead to loss of tension and consequent severe problems, such as cracking of the concrete or fracturing of the steel. This work addresses the problem of determining tension in embedded pre- and post-tensioned rods. The major problem with existing test techniques is that they use indirect and non-quantitative methods to determine whether there has been a loss of tension. We have developed an acoustic technique and sensor to make quantitative tension measurements in an embedded tensioned steel member. Although initially developed for civil works applications, this new acoustic technique is directly applicable to any concrete structure with steel members in tension, including bridges and heavily reinforced bunkers. Acoustic technology provides a method to measure the tension quickly, accurately, and quantitatively. Researchers at ERDC-CERL developed a theory and measurement technique for determining tensile stress in steel directly from ultrasonic measurements, and a procedure to simulate the ultrasonic environment inside a steel rod. An invention disclosure has been submitted on this acoustic technology.
See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, Florida on 1-4 December 2008. Published in the Proceedings of the Army Science Conference (26th), 2008. The original document contains color images.