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Fusion Bonded Epoxy Coating
Engineers and Researchers have found that fusion bonded epoxy coating is the practical and scientific way for protecting steel reinforcement against corrosion
Applying an epoxy coating to steel rebar prevents the chlorides from reaching the steel surface. And since the material is applied to the rebar at a mill away from the job site, it is not weather dependent and will not cause construction delays
Cracks in the concrete, allowing penetration of chloride bearing waters, is not a factor because the protection is applied on the bar surface where the problem is usually observed.
The most effective form of epoxy coating is the fusion bonded method. This allows the coating to achieve adhesion as the result of the heat-catalyzed reaction.
An epoxy coating is formed by combining an epoxy resin with the appropriate curing agents, filters, pigments, catalyst and leveling and flow control agents to achieve the desired characteristics
It is applied from an electrostatic charged powder state to a pre-heated rebar. The powder when comes in contact with the hot bar, it melts, gets and cures to a well adhered, continuous corrosion resistant coating.
The first fusion bonded epoxy coating designed specifically for reinforcing steel was put in the market in 1976. Since then, continuous research, design and testing have taken place which have enhanced and confirmed the effectiveness of fusion bonded epoxy coated rebar [FBECR] in preventing steel corrosion.
As well as providing the most effective solution to concrete degradation, FBECRs also provides the required flexibility to withstand 180 degrees bend over a short radius mandrel without affecting the coating. In addition they offer increased resistance to damage that can be caused by careless site handling.
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Powder coatings are 100% solid, finely ground fused particles and physically similar in appearance to sand. When the powder coating is heated, these fused particles melt to form continuous film, typically a very durable and chemical resistant film.
Corro-Coat EP-F 4003 used at Q-Coat is a fusion bond epoxy designed for use as an anti-corrosion suitable for applications on reinforcement bars at a thickness of 130 to 300 microns.
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The Fusion Bonding Process
The fusion bonded epoxy [FBE] coating process comprises of 9 stages:
Bar Surface Inspection
Check if there are any defects on the Bar surface which affects the coating
Surface Preparations
Prepare for coating by abrasion grit blasting
Preheating
Preheat the bar up to approximately 230 degrees centigrade with high frequency induction heating.
Electrostatic Spray Coating
In the powder coating chamber, the epoxy coating is uniformly applied at the specified thickness using electrostatic spray deposition
Heat Curing
The coating is cured using the residual heat in the bar. It is then force cooled with water
Quenching
Suppresses the excessive heat curing
Holidays inspection
The coating is electrically checked for holidays using low voltage contacting search electrodes
Other Inspections
Thickness, bending and impact resistance are also inspected
Packing
The coated bars are then carefully tied with nylon straps and bundles wrapped in protective sheeting, ready for loading & transportation
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