This specification outlines the criteria for fusion-bonded epoxy-coated deformed steel reinforcement bars designed to improve corrosion resistance in concrete structures. It details the coating composition, application techniques, and testing methods including adhesion, thickness, chemical and mechanical durability, as well as bond strength with concrete. The standard is crucial for manufacturers, engineers, and quality inspectors to guarantee the longevity and reliability of epoxy-coated reinforcement in aggressive environments.
Overview
This specification outlines the criteria for fusion-bonded epoxy-coated deformed steel reinforcement bars designed to improve corrosion resistance in concrete structures. It details the coating composition, application techniques, and testing methods including adhesion, thickness, chemical and mechanical durability, as well as bond strength with concrete. The standard is crucial for manufacturers, engineers, and quality inspectors to guarantee the longevity and reliability of epoxy-coated reinforcement in aggressive environments.
Audience
Contents
Structure
This section defines the coverage of fusion-bonded epoxy-coated deformed steel bars designed for corrosion protection in concrete. It explains the coating purpose, especially for environments with saline or industrial pollutants, and outlines the adhesion bend test procedure with mandrel sizing based on bar diameter, ensuring coating integrity.
Compilation of essential references, formulas, and tables including adhesion test conditions, mandrel diameters for bending, hardness testing requirements, and related ASTM and IS standards to supplement the specifications.
Describes the requirements for organic epoxy coating materials including pigment restrictions, chemical resistance properties, and coating thickness parameters with acceptance criteria and measurement guidelines.
Details the cleaning process involving abrasive blast cleaning to near white metal finish, the timing for coating application post-cleaning, prevention of rust bloom, and preparation for electrostatic powder application.
Outlines the procedure for applying epoxy coating by electrostatic dry powder spray, including timing constraints, curing protocols, sampling for thickness measurement, and acceptance criteria.
Specifies coating application, thermal curing, adhesion testing, mandrel sizing, gauge correction factors for thickness measurement, and quality control practices including patching and reprocessing.
Details the acceptable thickness range of 0.1 to 0.3 mm measured on the bar body using non-destructive magnetic gauges, including the calculation of correction factors and sampling requirements.
Describes the bend test method to assess coating adhesion, including bend angle, mandrel diameter selection, temperature control, and evaluation criteria to confirm coating integrity after bending.
Specifies chemical immersion tests in various solutions to verify chemical resistance, and mechanical tests such as abrasion and impact to ensure coating durability against physical damage.
Explains the pull-out test methodology, specimen requirements, bond strength calculations at specified slip values, coating integrity checks, and minimum bond strength criteria compared to uncoated bars.
Provides guidelines for safe handling to prevent coating damage, bundling methods with padding, identification tagging of bundles with cast number, grade and size, and retesting requirements if initial tests fail.
Defines acceptable limits for coating damage that need not be repaired, criteria for repair materials including compatibility and purchaser approval, and repair application locations and methods.
Outlines the requirement for manufacturers to provide a certificate upon request confirming compliance with thickness, adhesion, and patching standards, including reference to mandrel sizes and test conditions.
Details requirements for marking bars for identification, tagging bundles with key data, maintaining traceability through testing and acceptance procedures, and providing certificates upon purchaser demand.
Summarizes key testing protocols including adhesion bend tests, hardness measurements, abrasion resistance, retesting procedures upon failure, and criteria for batch acceptance or rejection.
Frequently Asked
As per IS 13620, the epoxy coating thickness on reinforcing bars must be between 0.1 mm and 0.3 mm after curing. Measurements are taken on the bar body between ribs using non-destructive magnetic gauges with a minimum of 15 readings per bar side. At least 90% of these measurements should fall within the specified range. Thicker coatings may be accepted if the bars remain unbent or unworked after coating, subject to mutual agreement.
IS 13620 prescribes a bend test where coated bars are bent through 120° around a mandrel whose diameter corresponds to the bar size. The bending is performed at a steady rate within 60 to 90 seconds at a temperature range of 25°C to 35°C. The bar’s longitudinal ribs are oriented perpendicular to the mandrel radius. Acceptance requires no visible cracking or detachment of the coating on the outside radius after bending. Partial steel fractures are not regarded as coating failures.
The steel bars must undergo abrasive blast cleaning to a near white metal finish, ensuring removal of mill scale, rust, and contaminants under good lighting. Coating must be applied promptly, ideally within 8 hours of cleaning. If rust bloom develops after cleaning, the bars should be re-blasted to remove the rust prior to coating application to ensure optimal adhesion and durability.
According to IS 13620, coating damage up to 40 mm² caused by fabrication or handling does not require repair. For damages exceeding this, repairs must use materials compatible with the original coating, chemically inert within concrete, approved by the purchaser, and applicable at the coating plant or onsite. Repairs should follow the coating manufacturer's guidelines. Visual inspections and holiday testing ensure coating continuity after repairs.
Bond strength is assessed through pull-out tests on 20 mm diameter bars, including both coated and uncoated specimens. The bond strength is calculated at slips of 0.025 mm and 0.25 mm, with failure defined when slip exceeds 0.2 mm under axial load. Additionally, the epoxy coating must pass adhesion bend tests with no visible cracking to confirm coating integrity. These tests ensure that coated bars maintain bond performance comparable to uncoated bars.
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