The anti-corrosion coating on the concrete surface has attracted more and more attention, but since the concrete is a non-metallic substrate, the thickness measuring instruments of the magnetic method and the eddy current method are not suitable for measuring the thickness of the protective coating film on the concrete surface. There are measuring instruments specially used for the thickness of protective coatings on concrete surfaces abroad, but the price is relatively expensive (the price is about 200,000 yuan per set).
In addition, there is also a destructive test method standard for coating film thickness on non-metallic surfaces in the American ASTM standard, namely: ASIM D4138-94 (revised in 2001) "Using destructive means to measure dry film thickness of protective anti-corrosion coating Standard Method for the measurement of the dry film thickness of an anti-corrosion coating by microscopic techniques and the observation of cut surfaces at precise angles on the coating film. The dry film thickness is measured by observing the angle cut line on the coating film through a microscope with a scale scale. Cuts are made on the anti-corrosion layer using different cutting instruments. American instrument manufacturers have produced this kind of test instrument according to the method standard. Recently, this kind of product has been sold in my country's domestic market, and Germany also has this kind of test product. The testing instrument can also be equipped with a special additional adhesion tool head, which can be used for scratch test, and the additional hardness tool head can be used for indentation hardness measurement. The picture below is a photo of this Thickness Gauge, which can be used to measure the thickness of the anti-corrosion layer on the surface of mixed soil, which belongs to a destructive testing method. At the same time, different knives can be configured to measure the hardness and adhesion of the film.
In the United States ASTM DII86 (non-destructive measurement standard for dry film thickness of non-magnetic coatings on iron-based substrates) and ASTMD1400J non-destructive measurement standard method for dry film thickness of insulating coatings on non-ferrous substrates, it is recommended Magnetic Thickness Gauge and eddy current Thickness Gauge.
