<![CDATA[The reuse of reinforcing steel bars in construction is a common practice to reduce material costs. However, bending and re-straightening processes may cause changes in mechanical properties and internal defects that are difficult to detect visually. Conventional material evaluation often relies on Destructive Testing (DT), which damages the specimen. Therefore, an accurate evaluation method is needed without damaging the material. This study aims to design and develop a portable and cost-effective Non-Destructive Testing (NDT) device to analyze the serviceability characteristics of reinforcing steel bars using the Ultrasonic Testing (UT) method based on Time of Flight (ToF). The analyzed parameters include ToF and signal amplitude. Tests were conducted on straight, bent, and re-straightening reinforcing bars with a length of 1 m and diameters of 12 mm and 14 mm. The results showed that the ultrasonic wave velocity in straight reinforcing bars was 4973.66 m/s (12 mm) and 4975.37 m/s (14 mm). In bent reinforcing bars, the velocity decreased to 4394.56 m/s (12 mm) and 4216.24 m/s (14 mm). In re-straightened reinforcing bars, the velocity increased to 4774.35 m/s (12 mm) and 4495.96 m/s (14 mm). These results indicate that the straightening process can partially restore the acoustic characteristics of reinforcing bars, making them closer to those of straight reinforcing bars. However, residual deformation still remains in the material.]]>
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