The utility model relates to the technical field of
calipers, and discloses a caliper for measuring a
steel bar protective layer, which comprises a main ruler, a strip-shaped groove is arranged on the main ruler, a fixed plate is fixedly connected to the inner wall of the strip-shaped groove, a
threaded rod is rotatably connected to the fixed plate, one end of the
threaded rod is in threaded connection with a movable plate, and the movable plate is in threaded connection with the strip-shaped groove. According to the utility model, the surface of concrete is ensured to be flat, then a proper measuring point is selected on a concrete member according to needs, the main ruler is flatly attached to the measuring point, then the rotating plate is rotated to drive the
threaded rod to rotate, and at the moment, the threaded rod rotates on the fixed plate; at the moment, it is ensured that the main ruler makes
close contact with the concrete surface, the scales on the main ruler are observed, the measured value of the thickness of the protective layer is recorded, rapid measurement can be achieved in a narrow space, and compared with a measurement method of a traditional steel ruler, the caliper can remarkably improve the detection efficiency and reduce labor intensity.