Working principle and calibrating significance of Film thickness Measurement Instrument for steel bar protective layer

Steel bar cover thickness measuring instrument, as the name suggests, is a non-destructive testing instrument for measuring the thickness of steel bar cover, so as to ensure the quality of construction.

working principle

The probe (with transmitting and receiving functions) of the steel bar cover thickness measuring instrument emits electromagnetic signals, and the steel bar in the cover produces a secondary induced magnetic field, which is received by the probe and processed by the instrument to obtain the measured value of the steel bar cover thickness or steel bar diameter. The instrument can also be used to measure the distribution of reinforcement.

Function and Calibration Significance

Reinforcement protective layer thickness measuring instrument is an instrument for non-destructive testing using electromagnetic principles, and is used to detect the thickness of the protective layer of building structures. Steel bar cover thickness measuring instrument is mainly used for the detection of steel bar distribution, diameter, direction, and concrete cover thickness quality in concrete structures of engineering buildings. The steel cover thickness measuring instrument can measure the position of the steel bar, the condition of the reinforcement, the thickness of the concrete cover, and the diameter of the steel bar on the surface of the concrete. In addition, the steel cover measuring instrument can also detect the position of the magnetic body and the electrical conductor in the concrete structure, such as the cable in the wall, the plumbing pipe, etc. The detection before construction can effectively avoid the damage of these facilities during construction. damage and reduce accidents. The steel bar cover thickness measuring instrument is an effective tool for construction process monitoring and quality inspection, so the accuracy and stability of the steel bar cover thickness measuring instrument are of great significance to the quality of the building.

In JJF 1224-2009 "Calibration Specifications for Reinforced Bar Cover and Floor Thickness Measuring Instruments", only the uncertainty of the measurement results affecting the indication error of the cover thickness when the steel bar cover thickness measuring instrument is calibrated for the cover thickness is given; but In actual work, the calibration of the steel bar diameter by the steel bar cover thickness measuring instrument needs to be carried out.

In the following, the standard block equipped with standard threaded steel bars is used as the calibration standard of the steel bar cover thickness measuring instrument, so as to carry out the uncertainty analysis of the measurement results of the steel bar diameter indication error measurement of the steel bar cover.