Fiberglass reinforcement, also called FRP reinforcement, is the main composite material in the market at present. It is reinforced with glass fiber and has the characteristics of light weight, high strength, corrosion resistance, easy cutting and non-magnetic properties. It is widely used in subway tunnels ( shield), coal mines, highways, bridges, airports, wharfs, stations, pavement and bridge decks, foundation pit construction, slope support, seawalls and dams, water conservancy projects and other fields.

Glass fiber bars are mainly used in engineering projects, so the quality control is very strict. Each batch of products must be inspected for appearance, dimensional deviation and tensile strength when leaving the factory, but when one of the following situations occurs, all items must be inspected in the form of standard requirements.

1. When a new product is put into production or when an old product is transferred to a factory for trial designation appraisal;

2. When the product has been discontinued for more than one year and resumed production;

3. After normal production, if there are major changes in materials and processes, which may affect product performance;

4. When the normal production of products has been completed for two years;

5. When there is a big difference between the factory inspection results and the last formal inspection.

There are 6 test items that must be done for the type inspection of glass fiber bars: product appearance, density, nominal diameter, straightness, tensile properties, and shear strength. Among them, the tensile properties include three items: tensile strength, ultimate tensile strain, and elastic modulus. The specific inspection contents are as follows:

1. Appearance: The shape should be in the form of a thread, the surface texture of the threaded rod body should be uniform, there should be no bubbles and cracks, the thread shape and pitch should be neat, and there should be no damage.

2. Density: The density of GFRP bar material is 1.9~2.2g/cm3, and the test should be carried out in accordance with the provisions of GB/T 1463-2005.

3. Nominal diameter: The nominal diameter should be in the range of 10mm-36mm, and the commonly used diameter specifications are 20mm, 22mm, 25mm, 28mm, 32mm. Different diameter specifications have differences in allowable deviation and straightness requirements, which are implemented in accordance with the standard.

4. Straightness: According to the standard requirements, the straightness requirement of 10mm-18mm diameter is ≤3mm/m; the straightness requirement of 20mm-28mm diameter is ≤4mm/m; the straightness requirement of 30mm-36mm is ≤5mm/m.

5. Tensile properties: according to the standard GB/T26743-2011.

1. Tensile strength: The standard value of anti-wave strength for glass fiber bars of different diameters is different, and the specific implementation is in accordance with the standard.

2. Modulus of elasticity: Requirement ≥40 GPa.

3. Ultimate tensile strain: Requirement ≥ 1.2%.

6. Shear strength: The test should be carried out in strict accordance with the provisions of Appendix B of the standard JG/T 406-2013, and the result should be ≥110 MPa.

Article source: China Steel Inspection and Testing