1 Scope
This document specifies the classification codes, order content, technical requirements, test methods, inspection rules, packaging, marking and quality certificates for fusion bonded epoxy coated reinforcement bars and finished reinforcement bars for concrete.
This document applies to reinforcing bars processed before and after coating and to finished bars processed before coating.
2 Normative references
The contents of the following documents constitute the essential provisions of this document through the normative references in the text. Among them, note the date of the cited documents, only the date of the corresponding version applicable to this document; do not note the date of the cited documents, the latest version (including all the revision of the list) applicable to this document.
GB/T 1499.1 Steel for reinforced concrete, Part 1: Hot-rolled smooth-round reinforcement
GB/T 1499.2 Steel for reinforced concrete, Part 2: Hot-rolled ribbed reinforcing bars
GB/T 1499.3 Steel for reinforced concrete Part 3: Reinforcing bars welded to mesh Y
GB/T 1768 Colour and varnish, determination of abrasion resistance, rotary rubber wheel method (GB/T 1768-2006, ISO 7784-2:1997, IDT)
GB/T 2101 General provisions for acceptance, packaging, marking and quality certification of steel sections
GB/T 3505-2009 Product geometrical specifications (rs) surface structure, contour method, terminology, definitions and surface structure parameters (ISO 4287:1997, 1DT)
GB/T 8923.1-2011 Surface treatment of steel prior to coating, visual assessment of surface cleanliness: Part 1: Rust grades and treatment grades of uncoated steel surfaces and steel surfaces after complete removal of the original coating (ISO 8501-1;2007,IDT)
GB/T13452.2-2008 Determination of the thickness of colour and varnish films (ISO 2808;2007,1DT)
GB/T 13788 Cold rolled ribbed steel bars
GB/T 20624.2-2006 Rapid deformation (impact resistance) test for colour paints and varnishes Part 2: Drop hammer test (small area punch)(ISO 6272-2:2002,IDT)
GB/T 50152 Standard for test methods for concrete structures
3 Terminology and definitions
The following terms and definitions apply to this document.
3.1
Coated bar
Fusion bonded epoxy coated reinforcement bars, welded wire mesh and finished bars.
3.2
Pre-coating conversion coating
Pre-treatment of metal surfaces prior to coating to promote adhesion of the coating and to improve corrosion and blister resistance.
4 Classification codes
4.1 Classification
Epoxy coated steel bars are classified according to the characteristics of the coating into Category A and Category B. Category A can be reprocessed after coating, while Category B should not be reprocessed after coating.
4.2 Designations
The name code for epoxy coated reinforcement is ECR.
4.3 Product type and examples
The type of epoxy coated reinforcement consists of the name code, the nature of the coating, the grade of the reinforcement and the diameter of the reinforcement.
5 Contents of the order
The contract for ordering according to this document shall include the following main elements: a) Product name;
b) the product type;
6 Technical requirements
6.1 Materials
6.1.1 Reinforcing steel
The quality of the rebar and finished rebar used for the epoxy coating shall conform to GB/T 1499.1 or GB/T 1499.2 or GB/T 1499.3 or GB/T 13788 or other product standards proposed by the demander. The surface of the steel should not have burrs, sharp corners and other defects that affect the quality of the coating, and should be free of oil, grease or paint pollution.
6.1.2 Epoxy powder
The application of epoxy powder to form the coating shall comply with the provisions of Appendix C C.2.
If the contract is stipulated, the powder manufacturer shall take a 0.2kg sample from each batch of epoxy powder and provide it to the user. Specimens shall be stored separately in closed containers and marked with the batch name.
6.1.3 Repair materials
The repair material shall be compatible with the fusion bonded epoxy coating and shall be inert in concrete. The repair material is suitable for use in factories or on site for the repair of damaged coatings on epoxy coated reinforcement.
6.2 Coating
6.2.1 Pre-coating treatment
The surface of the reinforcement shall be cleaned by blasting with steel grit prior to coating to the following quality:
a) the residual amount of rolled iron oxide shall not exceed 5%;
b) surface contaminants ≤ 30%;
c) The average roughness should be 50 um~70 um, with the average deviation using the Ra value in GB/T 3505-2009;
d) The surface should not be adhered with chlorinated substances;
e) The surface should meet the visual assessment of rust removal grade Sa2/grade as stipulated in GB/T 8923.1-2011. Only steel bars that meet the requirements can be coated.
In order to increase the bond between the rebar and the finished rebar and the coating, chemical and/or other pre-treatment cleaning methods are permitted. Note: With some powder coatings the rebar is pretreated in accordance with the coating instructions.
6.2.2 Application of the coating
The coating should be applied to the surface of the rebar as soon as possible after decontamination. The interval between decontamination of the rebar and the application of the coating should not exceed the time specified in Table 1 and there should be no oxidation visible to the naked eye on the surface of the rebar. If the relative humidity exceeds 85%, the coating operation should be stopped.
When coating, the surface preheating temperature range and the curing requirements after coating shall be in accordance with the coating material manufacturer's instructions. The surface temperature of the coated reinforcement shall be measured at least once every 30 minutes during the continuous coating process.
6.3 Quality assurance and test procedures
The quality assurance and test procedures during the production of epoxy coated reinforcement are as specified in Appendix C.
6.4 Coated reinforcement bars
6.4.1 Thickness of coating
The recorded values of the cured coating thickness shall meet the requirements of Table 2.
7 Test methods
7.1 Coating thickness
The coating thickness is measured in accordance with the provisions of method 7 of GB/T 134522-2008. Each recorded value of thickness is the average of 3 adjacent inter-rib thickness measurements. Measurements should be taken on opposite sides of the reinforcement and at least 5 roughly evenly spaced coating thickness records should be obtained along each side of the reinforcement (minimum 10 records per specimen).
7.2 Coating continuity
A wet sponge DC leak detector or equivalent method with a voltage of not less than 67.5 V and a resistance of not less than 80 kQ shall be used prior to delivery and tested in accordance with the instructions for the leak detector or equivalent method. The leak detector should have a fixed detection voltage and be calibrated and valid. The leak detector should be equipped with an indicator light or buzzer to indicate discontinuities in the coating. The probe should detect the entire surface of the coated reinforcement.
A wetting agent should be added to the water in which the sponge is immersed.
In-line leak detection is the recommended method. A hand-held leak detector should be used to check the accuracy of the in-line system at regular intervals. In order to obtain an accurate number of leaks, it is important to ensure that the sponge is always in contact with the coating being tested.
7.3 Coating bendability
For reinforcement bars, the bendability of the coating should be evaluated by bending the coated bar around the mandrel by 180° (after rebound). The bendability of the coating shall be tested by means of a bending tester. The longitudinal ribs of the ribbed reinforcement shall be placed in a plane perpendicular to the radius of the core axis of the bending tester. The bending test shall be carried out at a uniform angular speed of at least 8 r/min. The temperature of the test shall be 23 °C ± 5 °C. The bending test parameters for epoxy coated reinforcement shall be in accordance with the requirements of Table 4.
7.4 Coating adhesion
The adhesion of the coating shall be tested in accordance with C.2.2 and C.2.3 using the cathodic stripping and salt spray test methods.
8 Inspection rules
8.1 Classification of product inspection
Product inspection is divided into process control inspection, delivery inspection and type inspection.
8.2 Batch rules
Epoxy coated reinforcement should be accepted in batches. Each batch consists of the same production line, the same production process, the same nominal diameter, the same grade of reinforcing steel. The weight of each batch shall not be greater than 30 t.
8.3 Inspection items and sampling quantities
8.3.1 Process control inspection
The process control inspection items, times and methods for each batch of reinforcement shall be in accordance with the provisions of Table 5.
9 Packaging, marking and quality certificate
9.1 Packaging, marking and quality certification of coated reinforcement shall conform to the relevant provisions of G/T 2101.
9.2 Care shall be taken in the handling of the coated reinforcement. The slings for lifting the coated reinforcement should be made of high strength nylon belts, not steel wire ropes; the length of the coated reinforcement should be set up with a peal pivot point below 6 m, and a pivot point every 4 m if the length exceeds 6 m; the number of pivot points should be increased if the weight of the coated reinforcement exceeds 2 t. Prevent damage to the coating caused by collision and friction between the reinforcement and the sling and between the reinforcement and the steel. Coated steel should be handled horizontally and not dragged and thrown. Each bundle of coated reinforcement should be separated by a wooden partition; coated reinforcement exposed outside the workshop should be protected by a canvas wrap.
If the coating is stored outdoors for more than 2 months, protective measures should be taken to avoid exposure to sunlight, salt spray and atmosphere. If the coated reinforcement is stored in a corrosive environment, the coating should be effectively protected against damage. If the coated reinforcement is stored outdoors without a cover, the bundle should be labelled with the duration of outdoor storage. Coated reinforcement should be covered with an opaque material or other suitable protective cover. For bundles stacked in layers, the covering material shall be tightly covered. The cover should be securely fastened and air should be kept circulating around the coated reinforcement to avoid water condensation under the cover.
All coated reinforcement should be stored off the ground with a protective barrier.
The product type and batch number of coated and finished reinforcement, and the date of coating, shall be shown on the label and on the quality certificate.
Appendix A (Informative) Cross Reference List of Structural Numbers
Appendix B (Informative) List of technical differences and their causes
1 Scope
2 Normative references
3 Terminology and definitions
4 Classification codes
5 Contents of the order
6 Technical requirements
7 Test methods
8 Inspection rules
9 Packaging, marking and quality certificate
Appendix A (Informative) Cross Reference List of Structural Numbers
Appendix B (Informative) List of technical differences and their causes
