Monitoring of reinforced concrete short ties with the acoustic emission technique

Cracking in Reinforced Concrete (RC) structures may impact their durability and their structural integrity. Cracking is mainly influenced by stress distribution along the interface between steel and concrete. Thus, quantitative evaluation of steel-concrete bond, which is responsible of transferring load from steel bar to the surrounding matrix, and its effect on fracture properties is of major important. An experimental investigation on RC ties is reported in this paper. Tensile tests have been conducted on cubic specimens with different high adhesion reinforcement diameters. Those tests have been monitored continuously using the Acoustic Emission (AE) technique for a better evaluation of the damage process. The results show a good correlation between the load and the AE activity. AE signals with different characteristics have been observed during the different fracture stages. Parameters such as duration and energy increased with the loading level and can be used as indicators to detect the macrocracking of concrete. A parametric analysis is performed between average frequency and RA value. Ib-value of AE hits has been also investigated and decreases to 0.12 prior to the first macro crack