GB/T 39147-2020Steel fiber for concrete (English PDF)

3.1 Steel fiber

Short and thin fibers made of steel materials that can be randomly distributed in concrete.

3.2 length

The distance between the outer ends of the steel fiber.

3.3 Stretch length

The length of the profiled steel fiber after straightening under the condition of keeping the cross-sectional dimension unchanged.

3.4 Equivalent diameter

The diameter of a circle that is the same as the average cross-sectional area of steel fibers.

Note. For circular section steel fibers, the equivalent diameter is the same as the diameter of the steel fiber.

7.2.5 Weight deviation

The deviation of the net weight of the product in each package should not exceed ±1% of the rated weight.

7.2.6 Tensile strength

The nominal tensile strength of steel fiber shall conform to Table 3.The tolerance of steel fiber tensile strength is determined according to Table 4.

7.2.7 Modulus of Elasticity

After negotiation between the supplier and the buyer, the elastic modulus of the base material before the deformation of the steel fiber can be provided.

7.3 Application

7.3.1 Mixing

Forced mixing should be used for steel fiber concrete. The mixing process of steel fiber concrete should ensure that the steel fiber is evenly dispersed in the mixture without causing agglomeration.

The producer should provide mixing instructions to guide the method of adding steel fibers to concrete and operating procedures to avoid clumping.

7.3.2 Toughening effect of steel fiber on concrete

After negotiation between the supplier and the buyer, the manufacturer should provide the minimum content (kg/m3) that meets the following toughening effect requirements when required for structural applications.

Residual bending resistance when the notch displacement of the steel fiber concrete specimen reaches 0.5mm (or equivalent to the mid-span deflection of the specimen reaches 0.47mm)

When the tensile strength is greater than or equal to 1.50MPa and the notch displacement reaches 3.5mm (or equivalent to the residual mid-span deflection of the specimen reaching 3.02mm)

The residual flexural tensile strength is greater than or equal to 1.00MPa.

7.3.3 Workability of steel fiber concrete

After negotiation between the supplier and the buyer, when the application requires, the supplier shall determine and announce the Viber consistency value of the steel fiber concrete with the lowest content in 7.3.2.

7.3.4 Air content of steel fiber concrete

After negotiation between the supplier and the demander, when the application requires, when 30kg/m3 of steel fiber is added to the benchmark concrete, no water reducing agent is added.

Under the conditions, the increase in air content should not exceed 2%.

8.1 Shape

Use visual inspection to check the shape of the steel fiber one by one against the template diagram of the steel fiber shape to determine whether it does not meet the requirements of the factory shape.

8.2 Dimensions

8.2.1 Length

The measurement of steel fiber length should use a measuring tool (such as. vernier caliper) with a division value not greater than 0.1mm.

The length of the steel fiber shall be measured according to the steel fiber shape template diagram provided by the supplier, and the length shall be accurate to 0.1mm. When you need to measure stretch length

Straighten it by hand. If it is not possible to straighten it by hand, it should be straightened with a hammer of similar material on a wooden, plastic or copper surface. entire

During the straightening process, the fiber cross section should not change.

8.2.2 (equivalent) diameter

For circular cross-section steel fibers, the diameter measurement should use an outside diameter micrometer with an graduation of 0.01mm. In the same cross section along two

Measure the diameter in a vertical direction to the nearest 0.01mm. Calculate the average value, and the result should be rounded to 0.01mm.

For rectangular cross-section steel fibers, the fiber width (w) and thickness (t) should be measured with an outside diameter micrometer with an accuracy of 0.01mm. Steel fiber

The dimensional equivalent diameter is calculated according to formula (1).

For steel fibers with irregular cross-sections, the total mass (m) and extension length (ld) of steel fibers should be determined, and the mass should be accurate to

0.001g. The equivalent diameter of steel fiber is calculated according to formula (2).

8.3 Tensile strength

The tensile strength of steel fiber should be measured in accordance with the requirements of GB/T 228.1, and the measured maximum tensile value is divided by the measured steel fiber transverse

Cross-sectional area calculation.

The tensile strength of Class I steel fiber shall be determined by the metal wire or qualified steel fiber before deformation.

The tensile strength of Class II steel fiber shall be determined by the metal plate before deformation or qualified steel fiber.

The tensile strength of Type III, IV, and V steel fiber is measured by steel fiber, and the minimum length of steel fiber between the fixtures of the testing machine is 20mm. fiber

The nominal tensile strength is calculated by dividing the measured maximum tensile value by the fiber cross-sectional area, which is calculated based on the measured equivalent diameter. If using optical method

Method to determine the area of the cross-section, the measurement accuracy of the cross-section area and the tensile strength value obtained by dividing the maximum tensile value by the cross-sectional area at the fracture should be indicated.

Note. For shorter steel fibers, the test method can be determined through negotiation between the supplier and the buyer.

8.4 Bending performance

The bending test is carried out at 10°C~35°C in accordance with GB/T 238.The bending test should use an automatic bending test machine to

The 3.0mm support shaft is bent at a constant speed of 90° in two opposite directions in the same plane, and the specimen is bent 90° and returns to the original

The position is a bend, see Figure 1.The bending test can also be manually bent, but there should be suitable tooling to ensure that the steel fibers are in the same plane

Bending back and forth, and the bending angle of the steel fiber should be 90° each time. Record the number of final bends.

8.5 Modulus of Elasticity

The steel fiber elastic modulus test uses the base material before deformation to measure, and it can pass the stress and stress of the base material at 10% Rm and 30% Rm.

Change the calculation to get the elastic modulus. For Type I and Type II steel fibers, the elastic modulus can be tested according to the provisions of GB/T 228.1.

8.6 Surface quality

Use visual inspection for inspection.

8.7 Processing debris

Weigh and sample according to Table 4, record the sample weight as m0, and the accuracy of the weighing instrument is not less than 0.1g. Manually select the factors contained in the steel fiber

Adhesive sheets, iron filings and other impurities caused by poor processing and severe rust shall be weighed and recorded m1.The proportion of processed debris is calculated according to formula (3).

8.8 Weight deviation

Perform weight testing on randomly selected samples. The weighing instrument should be adjusted to the horizontal position before use, and the accuracy of the weighing instrument should not be greater than

0.1% of nominal weight.

8.9 Toughening effect of steel fiber in concrete

According to Appendix A, add steel fiber to the reference concrete, and determine the minimum content of steel fiber in the concrete to meet the toughening requirements according to Appendix B.

the amount. Refer to Appendix C for the classification of flexural performance of steel fiber concrete.

The number of steel fibers sampled shall be the minimum content in 7.3.2.

8.10 Workability of steel fiber concrete

The workability test method of steel fiber concrete shall be implemented in accordance with Chapter 6 of GB/T 50080-2016.In reference concrete according to appendix A

When adding steel fiber, the sample quantity of steel fiber shall be the lowest content provided in 7.3.2.The number of measurements is 1 time.

8.11 Air content of steel fiber concrete

The test method for the air content of steel fiber concrete is carried out in accordance with GB/T 50080-2016.The air content change deltaQ is calculated according to formula (4).

The air content of steel fiber concrete was tested twice and the average value was taken. The number of steel fiber sampling is as specified in 7.3.4.The sampling method is

The supply and demand parties decide through consultation.

Note. The performance comparison object of steel fiber concrete is the benchmark concrete performance. In the benchmark concrete, in addition to the steel fiber content of 0, other mix ratio parameters

Both are the same as steel fiber concrete, and the preparation methods and test systems of benchmark concrete and steel fiber concrete are consistent.

9.1 Inspection items

The steel fiber factory inspection items and sampling quantity are shown in Table 5.

9.2 Judgment rules

9.2.1 Batching rules

The quality of steel fiber shall be inspected by the supplier at the factory, and shall be inspected and accepted in batches. Each batch is of the same type, same size

The strength grade of steel fiber composition, each batch of the supplier should not exceed 40t. The demand-side re-inspection can appropriately increase the batch.

9.2.2 Re-inspection and judgment

If there is one or more unqualified items in the inspection results, double samples shall be taken to re-inspect the unqualified items.

If the product meets the requirements of this standard, the batch of products is qualified. If any item of the re-inspection result does not meet the requirements of this standard, the batch of products is judged as unqualified.

Note. The manufacturer's factory production control can refer to Appendix D.

10.1 Packaging

Steel fiber packaging can adopt corresponding packaging methods according to user requirements and transportation characteristics, but there should be moisture-proof measures.

10.2 Identification

The package should indicate the supplier's name, product name, product code, number of this standard, weight, and production date.

10.3 Transportation

General loading and unloading transportation methods can be used, but necessary measures should be taken to prevent rain, water, and snow intrusion.

10.4 Storage

Steel fiber should be stored in a clean, ventilated and dry warehouse, and should not be placed with corrosive materials.

A.1 Overview

This appendix evaluates the effect of steel fiber in concrete by specifying the composition and characteristics of the reference concrete.

Note. The purpose of designating reference concrete is to determine the general applicability of steel fibers in concrete.

A.2 General requirements

A.2.1 The test is carried out under standard laboratory conditions.

A.2.2 The design of the reference concrete shall meet the requirements of Table A.1.

A.2.3 The measurement of the properties of steel fiber concrete should use the maximum particle size in accordance with Table A.1.

A.2.4 When adding steel fibers to concrete, ensure that the steel fibers are evenly distributed in the concrete after mixing.

A.3 Equipment

A.3.1 Concrete mixer

The mixing of concrete should use forced concrete mixer.

A.3.2 Mould

The mold should be made of steel material to ensure that the size of the test piece is 150mm×150mm×550mm.

A.3.3 High frequency vibration table

The high-frequency shaking table shall be suitable for the vibration compaction requirements of beam concrete specimens in Appendix B.

A.4 Materials

A.4.1 Aggregate

The aggregate should be natural siliceous aggregate with a water absorption rate of less than 2%. It should be dried or air-dried before use. The measurement aggregate gradation should conform to JG/J52

Claim.

A.4.2 Mixing water

The mixing water should meet the requirements of JGJ63.

A.4.3 Cement

The cement should use GB 175-2007 P·O42.5 cement.

A.4.4 Additives

The admixture should meet the requirements of GB 8076.It is advisable to use high-efficiency water reducing agent to control the workability of concrete when preparing steel fiber concrete.

A.7 Concrete curing and storage

A.7.1 After pouring, the concrete test piece should be cured with a mold for 24h under the condition of (20±5)°C and covered with polypropylene film.

A.7.2 The mold is then removed, and the curing is continued for 27 days in a saturated calcium hydroxide solution at (20 ± 2) °C or in a standard curing room.

A.7.3 After the curing phase is completed, the test piece can be used for testing.

A.8 Report

Any set of benchmark concrete tests shall record the following information.

a) Mixing ratio, including the amount of dry aggregate, admixture (kg/m3) and specific mixing process;

b) water-cement ratio;

c) Date and time of production;

d) The particle size gradation of aggregate;

e) Maintenance and storage conditions;

f) The bending tensile strength value is accurate to 0.01MPa (average value and individual value);

g) This standard number.

Appendix D (Informative appendix)

Factory Production Control (FPC)

D.1 General

The manufacturer shall establish a document management system and continuously maintain the factory production control (FPC) system to ensure that the performance of the product meets the requirements of this standard.

Requirements, and its own performance requirements. The FPC system should include procedures, periodic inspections and tests and/or evaluations, and use these results to

Materials, other materials or components, equipment, production processes and products.

Any important changes that affect the performance of the product and the raw materials used, the production process and the control plan should be combined with the new fiber characteristics

The test data are recorded together in the manual or related documents.

The inspection, test or evaluation results should be recorded and filed, and the measures taken should also be recorded. When the control value is different from the standard

The measures taken when they match should also be recorded.

D.2 Equipment

All weighing, measuring and testing equipment should be checked and calibrated regularly in accordance with the procedures and standards specified in relevant documents.

D.3 Raw materials

To ensure the consistency of incoming materials, the specifications and inspection plans of all incoming materials should be documented.

D.4 Design procedure

The factory production control system should record all stages of product design, and clarify the inspection procedures and the person in charge of each design stage.

During the design process, all inspection results and corrective actions should be recorded. The record should record each design in sufficient detail and accuracy

Stages and inspection results.

D.5 Product testing and evaluation

The manufacturer shall establish relevant procedures to ensure the stability of the nominal value of product performance. The characteristics that should be controlled include.

---shape;

---Fiber coating;

---Size and tolerance;

---tensile strength;

---Bending requirements.

The minimum test frequency and test volume requirements are shown in Table D.1.