How to tell the difference between paint and fusion bonded epoxy coating

Hundreds of paint formulations are being sold in market each claiming the best benefits. Each paint has its own chemistry and set of properties so it is essential to match it with requirement of application to get the maximum advantage esp when value addition difference is too wide and the opportunity cost difference is too high eg. In functional coatings like rebars.

When pigments are fine tuned, it is difficult to differentiate between regularly painted rebar and fusion bonded epoxy coated rebar as visually both look alike. However with careful observations and some tests to validate the same it can be easily identified & differentiated between normally painted rebar and fusion bonded epoxy coated rebars.

ParameterPaint Fbec
Image
Raw materialContains VOC+solvents-pollution
Liquid
Lot of wastage due to overspray
Environment friendly
Powder
100% used
ProcessSand blasting
-health hazard
-poor Ra-poor adhesion
Primer coat+top coat
Brush applied, air cured, poor adhesion
Site application-unreliable quality
Abrasive blasting
Single uniform coat
Fusion bonded-strong adhesion
Plant applied-controlled quality
Properties VisualDull matt-like finish
Bulging
Air pockets
Sagging, dripping
Solid smooth finish
Almost uniform thickness
DamageEasily damaged
Corrosion spreads underneath film
Chips & scratches easily
Hard & tough film
Prevents spread of corrosion around damaged area
Scratch resistant
Sharp edgesDifficult to cover, less thicknessMore thick cover
Contour ribsFilled & coveredLess thickness
DurabilityFew years80-100 years
Tests
Cathodic Disbondment>4 mm<3mm
Applied Voltage ResistenceH2 Evolution & Rusting within a weeklasts more than 30 days
GlossLowHigh
Dielectric resistancepoorstrong
Film ThicknessLow and non-uniformUniform
Hardness< 16 Knoop>16Knoop
Salt spray-scratched panelvery less>1000Hrs
Boil Adhesion TestFailPass

Above table summarizes the salient differences between paint and FBEC which will be helpful to site engineers in achieving desired design life of RCC structures by protecting their rebars from undue corrosion.

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