Abstract: The present invention measures the strain caused by the shrink and expansion from the corrosion and examines the corrosion of a tendon for a long term with high sensitivity to improve the accuracy of the examination.

Abstract: The present invention is for measuring the diameter of a steel reinforcement rod in a concrete. Therein, a comparing rod is deposed outside of the construction and is corresponding to the steel rod to make the magnification rates of the steel rod and the comparing rod be the same. Then, the comparing rod and the steel rod are irradiated by a radioactive-ray source. And, then, a display is provided to show images of the rods to evaluate the size and the defect of the steel rod by the size and the shape of the comparing rod, so that the examination accuracy can be greatly improved and the examination result can be a reference for evaluating the construction safety.

Abstract: The present invention is a method for examining corrosion on a reinforcement steel. A sensor with a fiber Bragg grating is connected with a coupler; and the coupler is connected with a laser and an analyzer. Apply the sensor at a proper position on the reinforcement steel. A light source of the laser goes to the sensor through the coupler; and then the light passes the sensor and is transferred back to the analyzer. The analyzer can then figure out the strain out of the deformation and swell on the reinforcement steel owing to its corrosion by detecting the drift of the Bragg wavelength of the light. By doing so, the present invention obtains high sensitivity, strong corrosion sustainability and electromagnetic jam prevention so that the accuracy of the detection becomes higher and it can be widely applied to examine the corrosion on the reinforcement steel in a long term.