What is Fusion Bonded Epoxy Coating (FBE Coating)
Fusion Bonded Epoxy Coating also known as Fusion Bonded Epoxy powder Coating (also referred as “FBE Coating” or “FBEC”) is a high quality and high performance anti corrosion coating. It provides excellent protection for concrete reinforcing bars used in construction industry scenario.
Unlike most other coatings, Fusion Bonded Epoxy power Coating for coating rebars is not applied on site. Instead, the bars are coated in a controlled factory environment where critical factors like temperature and humidity are monitored.
Many bridges and infrastructure, such as buildings, experience from corrosion, which drastically reduces their service life, resulting in asset loss and loss of life. Steel loss is currently estimated to be several million tonnes in India alone.
Since 1973, epoxy coated steel has been used to prevent corrosion in RCC structures across the world. According to tests, FBEC is the most cost-effective technology for increasing the corrosion resistance of all RCC structures.
FBE Coating for rebars is not applied at the site. Instead, the rebars are coated in a strictly controlled factory process where epoxy powder is fusion bonded to the steel surface.
During the shot blasting process, the surface of the steel, reinforcing bars that will be coated must be cleaned by the impact of steel shots or grit. Before applying the coating, any rust blooms that have formed on the cleaned bars must be removed by blast cleaning.
As per IS: 13620: 1993, the coating must never be delayed for longer than 8 hours after cleaning.
The powder is applied electrostatically to the cleaned surface of a hot steel bar using an electrostatic spray gun, where it fuses, melts down and cures to an adherent, continuous and chemically cross linked protective film. This coating significantly reduces the amount of current required for cathodic protection to prevent corrosion.
In other words, The powder dissolves and turns into a liquid state. The fluid, flowing liquid FBE layer attaches to the steel surface it is sprayed to and quickly hardens by chemical cross-linking with the help of heat. “Fusion bonding” is the name of this procedure.
The thickness of coating shall be maintained between 100 microns to 300 microns after curing. For acceptance of atleast 90 percent of all coatings thickness shall be within above range.
The coating shall be visually inspected after curing for continuity of the coating and shall be free from holes, voids, contamination, cracks and damaged area discernible tot he unaided eye.
Moreover, Every factory / plant that are capable of coating should follow any stringent specifications such as ASTM, ISO or BIS. Besides, qualified and trained technical staff should endure that the coating is applied and tested in a profession manner.
Various types of tests are performed in the laboratory such as chemical resistance, salt spray, applied resistance, cathodic disbondment, abrasion resistance, thickness test, chloride permeability, Impact test etc.
For each manufacturing slot, one bar for every tonne up to 16 mm in diameter, two for every tonne between 16 and 25 mm in diameter, and four for every tonne beyond 25 mm in diameter will be used to test the coating’s adherence.
Coated bars that are represented by samples but do not fulfill the standards must be rejected. This bar could well be cleaned, re-coated, and submitted for an acceptance test again in accordance with the requirements after being stripped of its coating.
When the damage area is 40 mm square or smaller, coating damage caused by fabrication and handling does not need to be rectified. Any damaged area that is greater than 40 mm square must be patched. The maximum amount of damage cannot be greater than 2% of each bar’s surface area.
After that, all tests and inspection shall be made at the place of manufacture prior to delivery.
- The coated bars shall be carefully handled. The bundles of coated bars shall bot be dragged or dropped during handling.
- Avoid rubbing of coated bars against each other or hard surface, which may damage the coating during handling.
FBE Coating capacity to withstand a wide range of environmental conditions has been laboratory and field tested to prove that it will last for atleast three decades. Thus, the concrete structure itself gets an extended lease of life, resulting in considered cost savings in construction works to the clients.
- Excellent Corrosion Protection
- Cost effective life cycle
- High resistance to cathodic disbondment
- Resistant to chemical contaminants
- Extended service life
- Good abrasion and impact resistance
- Excellent steel adhesion
- Resistance against heat
Moreover, FBE Coating is frequently used to prevent corrosion of steel pipe used in pipeline construction, rebar and couplers in structure constructions, and dowel bars in cement concrete pavements.
- Simple and quick procedure
- Less wastage of material
- Rapid production rate
For more details, please refer to the following
- IS 13620: 1993 – Fusion Bonded Epoxy Coated Reinforcing bars specifications.
- ASTM A775 / A775 M – Standard Specification for Epoxy Coated Steel Reinforcing Bars.
- ISO 14654: 1999 – Epoxy coated steel for the reinforcement of concrete.
- JIS G 3112: 2010 – Steel bars for concrete reinforcement.
- NACE SP0395 – 2013 – Fusion Bonded Epoxy Coating on steel reinforcing bars.
- OPSS 1442 – Epoxy Coated reinforcement steel bars for concrete
If you like this article, please do share this with your friends
And, tell us your queries in the below comment box.
Also Read: What is UHPFRC?