Non-destructive hardening test of embedded rebar of concrete

One important parameter in assessing the carrying capacity of reinforced concrete (RC) structures is steel strength. Difficulty exists in obtaining steel intensity data using nondestructive testing (NDT) methods for complete RC structures. Obtaining the steel strength is difficult for carrying capacities with differing steel qualities within the structure. As a result, positions of plastic hinges are varied. While several factors affect the hardness of the metal, the quality differs within the same metal material. However, RC uses comparatively mild steel. Nine steel beams were tested on their hardness and strength. These nine steel beams were embedded in RC to create an authentic simulation and underwent NDT. Taking into account experimental errors from the equipment, the confidence level was set at 95% (p<0.05). Under these conditions, the steel was classed as SD420 (SD=steel deformed) when hardness values were higher than 418HL (HL=Leeb Hardness) and SD280 when values were less than 354HL. According to the experimental results, on-site testing of steel hardness and grading provides older structures with analytical parameters to judge its load/(seismic) capacity.