Usefullness of non-destructive measurements in the diagnosis of tendon ducts in the post-tensioned concrete girders

• Methodology of complementary NDT investigation of post-tensioned elements. • Test results of the unique buildings structure in the global scale. • Complementary usage of the impact echo and ultrasonic tomography. • Technical state evaluation of the high-rise building bearing structure. This article addresses critical issues in the integrity of tendon ducts in post-tensioned concrete girders, which are essential load-bearing elements of two high-rise buildings in operation for forty years. The study aims to identify technological imperfections in these ducts through a novel methodology incorporating in situ non-destructive testing techniques not previously documented in the literature. The research focuses on determining the number and location of tendon ducts, detecting vertical and horizontal deviations of tendons from their designed positions, and identifying imperfections in cement grout filling. By implementing three complementary non-destructive methods, electromagnetic testing, ultrasonic tomography, and impact-echo, the study provides robust results, validated through borehole inspections. The findings contribute new knowledge that addresses gaps in current literature, enhancing the understanding and maintenance of post-tensioned concrete structures. Furthermore, the methodology has practical applications for assessing both high-rise buildings and post-tensioned bridges.