Reliability of Acoustic Emission as a Technique to Detect Corrosion and Stress Corrosion Cracking on Prestressing Steel Strands

摘要

Corrosion of prestressing strands is one of the main causes of deterioration of civil engineeringstructures, hence the need of monitoring these cables on real-time in order to avoid any accident. Thisexperimental work was aimed at investigating the ability of acoustic emission (AE) technique fordetection and monitoring of corrosion evolution and failure of strands. First, accelerated corrosion testswith ammonium thiocyanate were performed on a central wire cable without applied force and on atensioned strand to 80% of guaranteed ultimate tensile strength have enabled to collect and to comparethe acoustic responses of phenomena occurring during the corrosion of wire and cable, even those ofphenomena very little emissive, such as rupture of the passive film. Then, an accelerated corrosion testunder cathodic polarization until failure was achieved on a tensioned cable. Finally, the analysis of thefailure process used the pattern recognition classification with Visual Class program. The results haveshown that the fracture mechanism of the stress corrosion cracking process is associated with hydrogenabsorption. It has been proven that AE is a very useful technique to detect and evaluate corrosion andfailures of high-strength steel strands.