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Epoxy coated rebar

 
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venkatsuba
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Joined: 26 Jan 2003
Posts: 8

PostPosted: Mon Apr 27, 2009 8:57 am    Post subject: Epoxy coated rebar Reply with quote

Dear sefians
 
I received an assignment from my mgmt to submit a REPORT  on “Epoxy coated rebar”.  
 
The details I am going present are provided below. Kindly provide your comments.
 
Epoxy Coated Rebar
Causes for steel rebar corrosion
Deterioration of Rebar can occur within concrete structures due to:
·         Corrosion of reinforcement
·         Sulfate and chloride attack
·         Salt weathering
·         Cracking due to shrinkage
·         Thermal gradients
·         Aggregate-cement reactivity

Advantages of Epoxy coating
·         Protection - Epoxy coated rebar is designed to protect the rebar against rust and corrosion. Applying an epoxy coating to steel rebar prevents oxygen and chlorides from reaching the steel surface reducing corrosion.

·         Environmentally friendly materials - Unlike many paints, the fusion-bonded epoxy coatings used for steel reinforcement do not contain appreciable solvents or other environmentally hazardous substances.
Disadvantages of Epoxy coating
·         Special Handling - ECR requires delicate handling to prevent damage to the epoxy coating. Any damage to the coating prior to placement will compromise the corrosion protection. Special handling must be used at the fabrication plant, in transit to the site and during handling and storage to the site. It is essential that damage to the coating is minimized.
 ·         UV damage - ECR coatings break down under UV ray exposure.
 ·         Touch up after placement may be required due to scratching and chipping during transport and placement
 ·         Coating inconsistencies - ECR specifications allow for a percentage of the bar to have holidays and pinholes, compromising its protection mechanisms before it reaches the job site.
 ·         Abrasion resistance - The coating lacks abrasion resistance, and thus is easily damaged in transport to the job site and installation.
·         Poor bond to concrete - Loss of bond strength as a result of the epoxy coating
 ·         Under film corrosion - ECR coatings are permeable and once corrosion begins, it spreads throughout the bar underneath the epoxy film.
·         Installation conditions - ECR coatings may crack when handled in temperatures less than 50 F.
 ·         Increased corrosion process - Pin holes or discontinuity of the epoxy layer on a bar will enhance the corrosion process faster and more aggressive than in the case of a bare uncoated bar.
Alternates for avoiding epoxy coated rebar
 Following measures shall be adopted instead of using epoxy coated rebar for avoiding corrosion.  
1.    Cement shall be Sulphate resistant cement.
2.    Applying protective coating for the Horizontal and vertical concrete faces underground exposed to soil.  
3.    Minimum thickness of the Blinding concrete below foundations shall be 100 mm.
4.    Quality concreting and consolidation procedures

**** End***
 
Thanks & Regards
VENKAT 

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Dr. N. Subramanian
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PostPosted: Mon Apr 27, 2009 2:34 pm    Post subject: Epoxy coated rebar Reply with quote

Dear Mr. Venkat:

What do you mean by "ECR specifications allow for a percentage of the bar to have holidays"? The statement "Poor bond to concrete" is not correct. You may change it to reduced bond to concrete. Similarly "ECR coatings are permeable" is wrong. I am not sure whether"Pin holes or discontinuity of the epoxy layer on a bar will enhance the corrosion process faster and more aggressive than in the case of a bare uncoated bar" is correct or not. What do you mean by "Blinding concrete"?!

Dr.N.Subramanian









--- On Mon, 4/27/09, venkatsuba <forum@sefindia.org> wrote:
Quote:
From: venkatsuba <forum@sefindia.org>
Subject: [SEFI] Epoxy coated rebar
To: general@sefindia.org
Date: Monday, April 27, 2009, 6:21 PM

Dear sefians

I received an assignment from my mgmt to submit a REPORT on “Epoxy coated rebar”.

The details I am going present are provided below. Kindly provide your comments.

Epoxy Coated Rebar
Causes for steel rebar corrosion
Deterioration of Rebar can occur within concrete structures due to:
· Corrosion of reinforcement
· Sulfate and chloride attack
· Salt weathering
· Cracking due to shrinkage
· Thermal gradients
· Aggregate-cement reactivity

Advantages of Epoxy coating
· Protection - Epoxy coated rebar is designed to protect the rebar against rust and corrosion. Applying an epoxy coating to steel rebar prevents oxygen and chlorides from reaching the steel surface reducing corrosion.

· Environmentally friendly materials - Unlike many paints, the fusion-bonded epoxy coatings used for steel reinforcement do not contain appreciable solvents or other environmentally hazardous substances.
Disadvantages of Epoxy coating
· Special Handling - ECR requires delicate handling to prevent damage to the epoxy coating. Any damage to the coating prior to placement will compromise the corrosion protection. Special handling must be used at the fabrication plant, in transit to the site and during handling and storage to the site. It is essential that damage to the coating is minimized.
· UV damage - ECR coatings break down under UV ray exposure.
· Touch up after placement may be required due to scratching and chipping during transport and placement
· Coating inconsistencies - ECR specifications allow for a percentage of the bar to have holidays and pinholes, compromising its protection mechanisms before it reaches the job site.
· Abrasion resistance - The coating lacks abrasion resistance, and thus is easily damaged in transport to the job site and installation.
· Poor bond to concrete - Loss of bond strength as a result of the epoxy coating
· Under film corrosion - ECR coatings are permeable and once corrosion begins, it spreads throughout the bar underneath the epoxy film.
· Installation conditions - ECR coatings may crack when handled in temperatures less than 50 F.
· Increased corrosion process - Pin holes or discontinuity of the epoxy layer on a bar will enhance the corrosion process faster and more aggressive than in the case of a bare uncoated bar.
Alternates for avoiding epoxy coated rebar
Following measures shall be adopted instead of using epoxy coated rebar for avoiding corrosion.
1. Cement shall be Sulphate resistant cement.
2. Applying protective coating for the Horizontal and vertical concrete faces underground exposed to soil.
3. Minimum thickness of the Blinding concrete below foundations shall be 100 mm.
4. Quality concreting and consolidation procedures

**** End***

Thanks & Regards
VENKAT
     



     



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SINHARAYAK
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PostPosted: Tue Apr 28, 2009 4:38 am    Post subject: Epoxy coated rebar Reply with quote

Dear Shri Venkat,

Could you please highlight the cost comparison between for using TMT rebars verses epoxy coated TMT rebars for industrial construction.

With regards,

AK Sinha Ray


From: venkatsuba [mailto:forum@sefindia.org]
Sent: Monday, April 27, 2009 6:22 PM
To: general@sefindia.org
Subject: [SEFI] Epoxy coated rebar


Dear sefians

I received an assignment from my mgmt to submit a REPORT on “Epoxy coated rebar”.

The details I am going present are provided below. Kindly provide your comments.

Epoxy Coated Rebar
Causes for steel rebar corrosion
Deterioration of Rebar can occur within concrete structures due to:
· Corrosion of reinforcement
· Sulfate and chloride attack
· Salt weathering
· Cracking due to shrinkage
· Thermal gradients
· Aggregate-cement reactivity

Advantages of Epoxy coating
· Protection - Epoxy coated rebar is designed to protect the rebar against rust and corrosion. Applying an epoxy coating to steel rebar prevents oxygen and chlorides from reaching the steel surface reducing corrosion.

· Environmentally friendly materials - Unlike many paints, the fusion-bonded epoxy coatings used for steel reinforcement do not contain appreciable solvents or other environmentally hazardous substances.
Disadvantages of Epoxy coating
· Special Handling - ECR requires delicate handling to prevent damage to the epoxy coating. Any damage to the coating prior to placement will compromise the corrosion protection. Special handling must be used at the fabrication plant, in transit to the site and during handling and storage to the site. It is essential that damage to the coating is minimized.
· UV damage - ECR coatings break down under UV ray exposure.
· Touch up after placement may be required due to scratching and chipping during transport and placement
· Coating inconsistencies - ECR specifications allow for a percentage of the bar to have holidays and pinholes, compromising its protection mechanisms before it reaches the job site.
· Abrasion resistance - The coating lacks abrasion resistance, and thus is easily damaged in transport to the job site and installation.
· Poor bond to concrete - Loss of bond strength as a result of the epoxy coating
· Under film corrosion - ECR coatings are permeable and once corrosion begins, it spreads throughout the bar underneath the epoxy film.
· Installation conditions - ECR coatings may crack when handled in temperatures less than 50 F.
· Increased corrosion process - Pin holes or discontinuity of the epoxy layer on a bar will enhance the corrosion process faster and more aggressive than in the case of a bare uncoated bar.
Alternates for avoiding epoxy coated rebar
Following measures shall be adopted instead of using epoxy coated rebar for avoiding corrosion.
1. Cement shall be Sulphate resistant cement.
2. Applying protective coating for the Horizontal and vertical concrete faces underground exposed to soil.
3. Minimum thickness of the Blinding concrete below foundations shall be 100 mm.
4. Quality concreting and consolidation procedures

**** End***

Thanks & Regards
VENKAT  





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venkatsuba
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Posts: 8

PostPosted: Tue Apr 28, 2009 7:00 am    Post subject: Epoxy coated rebar Reply with quote

Dear Dr.N.S
 
Thank you for the reply.
 
ECR specs allow to use some percentage of bars which are not coated properly or fully or with less number of coats (Coating inconsistencies).
 
And,
 
Blinding concrete is nothing but non-structural concrete placed on top of soil at founding level on which the foundation slab rests. It will protect and form a leveled surface for the foundation. The top of blinding concrete will be painted with 2 coats of epoxy water proofing coat to avoid concrete base from suphate/chloride attack.
 
Regards
VENKAT


On Mon, Apr 27, 2009 at 6:50 PM, drnsmani <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote]  Dear Mr. Venkat:

What do you mean by "ECR specifications allow for a percentage of the bar to have holidays"? The statement "Poor bond to concrete" is not correct. You may change it to reduced bond to concrete. Similarly "ECR coatings are permeable" is wrong. I am not sure whether"Pin holes or discontinuity of the epoxy layer on a bar will enhance the corrosion process faster and more aggressive than in the case of a bare uncoated bar" is correct or not. What do you mean by "Blinding concrete"?!

Dr.N.Subramanian









--- On Mon, 4/27/09, venkatsuba wrote:
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P.K.Mallick
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PostPosted: Tue Apr 28, 2009 6:08 pm    Post subject: Reply with quote

COMPARISON OF STANDARD EPOXY COATING APPLICATION SPECIFICATIONS.


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COMPARISON OF STANDARD EPOXY COATING APPLICATION SPECIFICATIONS.

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Dr. N. Subramanian
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PostPosted: Tue Apr 28, 2009 8:23 pm    Post subject: Re: Epoxy coated rebar Reply with quote

Dear Er. Venkat,

You may be interested in reading debate on fusion bonded epoxy-coated rebars by Mr Kar and Er Singha Roy-See the  link:

http://www.icjonline.com/forum/forum_jan2004.pdf

Best Wishes
Subramanian


[quote="venkatsuba"]Dear Dr.N.S
 
Thank you for the reply.
 
ECR specs allow to use some percentage of bars which are not coated properly or fully or with less number of coats (Coating inconsistencies).
 
And,
 
Blinding concrete is nothing but non-structural concrete placed on top of soil at founding level on which the foundation slab rests. It will protect and form a leveled surface for the foundation. The top of blinding concrete will be painted with 2 coats of epoxy water proofing coat to avoid concrete base from suphate/chloride attack.
 
Regards
VENKAT


On Mon, Apr 27, 2009 at 6:50 PM, drnsmani <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
  Dear Mr. Venkat:

What do you mean by "ECR specifications allow for a percentage of the bar to have holidays"? The statement "Poor bond to concrete" is not correct. You may change it to reduced bond to concrete. Similarly "ECR coatings are permeable" is wrong. I am not sure whether"Pin holes or discontinuity of the epoxy layer on a bar will enhance the corrosion process faster and more aggressive than in the case of a bare uncoated bar" is correct or not. What do you mean by "Blinding concrete"?!

Dr.N.Subramanian









--- On Mon, 4/27/09, venkatsuba wrote:
--auto removed--

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rajmane
...
...


Joined: 26 Jan 2003
Posts: 160
Location: Chennai

PostPosted: Wed May 20, 2009 5:15 am    Post subject: slightly revised posting on concrete mix design Reply with quote

20 May 2009

Dear Er Renjith and Dr N Subramanian

• Dr NS clearly pointed out that concrete mix design is for target
compressive strength, which is expected to be the average (meaning the
population itself) when large number of specimens are collected over a
period and tested. However, at any particular time/instant, we may have
only so called ‘a few test results’ available, then, the computed
average strength of these can not match the target strength of the
concrete population, statistically speaking. Hence, a computed mean
value from the test results is accepted with some acceptable level of
confidence. This is the reason why the Clause 16 of IS 456:2000 and
SP:24-1983, pp.37 for the acceptance criteria, considers the mean of
four consecutive tests and this value should be greater than fck+4 N/mm2
(or fck+0.825*SD, whichever is larger, SD = Standard deviation).
• Statistically, occurrence of individual test being less than fck-4
N/mm2 is supposed very low and hence, in a normal construction site of
reasonable quality control, fck-4 may not or let us say should not occur
often to cause alarm!
• As per Clause 15.4, we must note that the test result of the sample is
the average of the strength of three specimens. The individual test
specimen result should be not considered at all. the ‘individual test
result’ of Col (3) of Table 11 of IS 456 is always average of say
minimum three specimens and not the individual specimen itself
• It would be interesting some more elaborate details are made available
for Table 11, especially based statistics, and not general concrete
related terms alone!

With best wishes and thanks

Rajamane N P
Director-grade-scientist & Head, Concrete Composites Lab, Structural
Engineering Research Centre, CSIR, Taramani, Chennai 600113 India
(Secretary, Indian Concrete Institute (ICI), Tamil Nadu Centre) Email :
rajmane@sercm.org,rajmane@sercm.csir.res.in,rajamanenp@yahoo.co.uk

(Kindly note that the above views are personal and not necessarily
represent the view of SERC as a whole)

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rjs_sjs
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Joined: 15 May 2013
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PostPosted: Wed May 15, 2013 1:13 pm    Post subject: Re: Epoxy coated rebar Reply with quote

Dear Friends

I need the names of companies who manufacture

Epoxy Coated TMT Bars  &

Corrossion resistance rebars

Kindly share

Thanks & regards
Rajendra
rjs_sjs@in.com

SINHARAYAK wrote:
Dear Shri Venkat,

Could you please highlight the cost comparison between for using TMT rebars verses epoxy coated TMT rebars for industrial construction.

With regards,

AK Sinha Ray


From: venkatsuba [mailto:forum@sefindia.org]
Sent: Monday, April 27, 2009 6:22 PM
To: general@sefindia.org
Subject: [SEFI] Epoxy coated rebar


Dear sefians

I received an assignment from my mgmt to submit a REPORT on “Epoxy coated rebar”.

The details I am going present are provided below. Kindly provide your comments.

Epoxy Coated Rebar
Causes for steel rebar corrosion
Deterioration of Rebar can occur within concrete structures due to:
· Corrosion of reinforcement
· Sulfate and chloride attack
· Salt weathering
· Cracking due to shrinkage
· Thermal gradients
· Aggregate-cement reactivity

Advantages of Epoxy coating
· Protection - Epoxy coated rebar is designed to protect the rebar against rust and corrosion. Applying an epoxy coating to steel rebar prevents oxygen and chlorides from reaching the steel surface reducing corrosion.

· Environmentally friendly materials - Unlike many paints, the fusion-bonded epoxy coatings used for steel reinforcement do not contain appreciable solvents or other environmentally hazardous substances.
Disadvantages of Epoxy coating
· Special Handling - ECR requires delicate handling to prevent damage to the epoxy coating. Any damage to the coating prior to placement will compromise the corrosion protection. Special handling must be used at the fabrication plant, in transit to the site and during handling and storage to the site. It is essential that damage to the coating is minimized.
· UV damage - ECR coatings break down under UV ray exposure.
· Touch up after placement may be required due to scratching and chipping during transport and placement
· Coating inconsistencies - ECR specifications allow for a percentage of the bar to have holidays and pinholes, compromising its protection mechanisms before it reaches the job site.
· Abrasion resistance - The coating lacks abrasion resistance, and thus is easily damaged in transport to the job site and installation.
· Poor bond to concrete - Loss of bond strength as a result of the epoxy coating
· Under film corrosion - ECR coatings are permeable and once corrosion begins, it spreads throughout the bar underneath the epoxy film.
· Installation conditions - ECR coatings may crack when handled in temperatures less than 50 F.
· Increased corrosion process - Pin holes or discontinuity of the epoxy layer on a bar will enhance the corrosion process faster and more aggressive than in the case of a bare uncoated bar.
Alternates for avoiding epoxy coated rebar
Following measures shall be adopted instead of using epoxy coated rebar for avoiding corrosion.
1. Cement shall be Sulphate resistant cement.
2. Applying protective coating for the Horizontal and vertical concrete faces underground exposed to soil.
3. Minimum thickness of the Blinding concrete below foundations shall be 100 mm.
4. Quality concreting and consolidation procedures

**** End***

Thanks & Regards
VENKAT  





Quote:
This Message was sent from Indian Oil Messaging Gateway, New Delhi, India. The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments.



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