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Comparison of Epoxy coated rebar vs CPCC rebar vs CRS rebar

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By
Sourav Dutta
Manager-Civil
Ion Exchange India Limited

Now-a-days for controlling rust/corrosion of rebar some extra treatment is being carried out on rebar, making it more resistant to rusting/corrosion under unfavorable circumstances. Some of these treated rebars normally used are: (1) Fusion bonded epoxy coated rebar, (2) Cement-polymer composite coated rebar,(3) Corrosion resistant steel (CRS) rebar. The following comparison is being made aiming to give a clear cut idea on advantages/disadvantages of each type, which might help and give an idea to construction industry for decision making of selection of any particular type.

Sl. No. Parameter Fusion bonded epoxy coated rebar Cement-polymer composite coated (CPCC) rebar Corrosion resistant steel (CRS) rebar
 

1

Corrosion Resistance Technology For protection of reinforcing bars against corrosion, epoxy coating is done on these bars by electrostatic spraying of fusion bonded epoxy powder. For protection of reinforcing bars against corrosion, coating of rapid setting primer followed by a coat of cement polymer sealing product is done. For protection of reinforcing bars against corrosion, chemical composition of rebar is made such as to develop inherent corrosion resising property.
 

2

 

BIS code

 

BIS13620-1993

No BIS code available. Developed by CECRI, Karaikudi. They have the detailed specification of chemicals and quality control with them. No BIS code available for CRS yet. Complying to BIS1786-2008 500D.
3 Manufacturing process control Difficult, as it needs to pass some critical procedures as per BIS. Difficult, as it involves various steps like surface preparation, coating application on rebar. Easier to control, as it is dependant on mother billet composition.
 

4

 

Damage possiblity

A coating of 0.1-0.3mm on external surface of rebar and liable to damage. Performance of the system depends upon least defect in the coating.  

It can be brush applied or sprayed and hence defects in the coating can be patch repaired.

 

Inherent property of rebar itself. No chance of damage/change in property.

5 Bond strength of rebar About 20% less strength than conventional reinforcing bars, due to the coating. Has good bond strength and hence bond between coated rod and concrete unaffected, as per CECRI. No effect on bond strength.
 

6

 

Handing

Special procedure is there for handling such rebar, otherwise the coating may get damaged. Even dropping or dragging such rebar is prohibited.  

Care to be taken while handling such rebar, otherwise the coating may get damaged.

 

No restriction in handling procedure.

 

7

Fabrication (Cutting) Chance of damage in coating during fabrication. Exposed edge of rebar will be affected by corrosion. Chance of damage in coating during fabrication. Exposed edge of rebar will be affected by corrosion.  

Normal practice like conventional rebar.

8 Bending Chance of disbonding in coating during bending. Chance of disbonding in coating during bending. Bending of rebar to be completed prior to coating. Normal practice like conventional rebar.
9 Welding Not advisable as coating get damaged during welding. Not advisable as coating get damaged during welding. No special care is required.
10 Usage of couplers Threaded portion of rebar without coating for fixing couplers leads to corrosion. Threaded portion of rebar without coating for fixing couplers leads to corrosion. Threading and coupler usage is not an issue due to inherent property of rebar.
 

11

 

Extent of protection

No measurement of extent of protection to rebar due to the coating, as per BIS. Smallest damage in coating can initiate corrosion under severe environment.  

This system is newly developed by CECRI and the long term results are not known.

 

About 25% lower rate of corrosion compared to conventional rebar.

 

 

12

 

 

Cost saving

Cost higher compared to conventional rebar typically by Rs 6000-13000/MT, due to the coating. Moreover, due to less bond strength, more development length required, leading to more cost.  

 

Cost higher compared to conventional rebar typically by Rs 5000-8000/MT, due to the coating.

 

 

Cost higher compared to conventional rebar by Rs 2500-3000/MT.

We at engineeringcivil.com are thankful to Er. Sourav Dutta for submitting this paper to us. We hope this paper will be helpful for the whole construction industry in general.

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