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[SEAOC] Re: [SEAOC] Epoxy Coated vs. Galvanized Rebars[Subject Prev][Subject Next][Thread Prev][Thread Next]
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- Subject: [SEAOC] Re: [SEAOC] Epoxy Coated vs. Galvanized Rebars
- From: "Hunt, Tom" <tom.hunt(--nospam--at)fluordaniel.com>
- Date: Thu, 06 Jun 1996 13:09:00 -0800
If you are talking about the final in place condition of the wall and your flood wall is for a non-marine facility then neither epoxy coated rebar or galvanized rebar will be of much value. The two main chemical attacks on concrete are sulphates and chlorides. High concentrations of sulphates will attack the cement paste. The solution for this is to use either Type II or Type V sulphate resistant cements. The chlorides (salt) have little direct effect on the concrete paste/aggregate but will obviously corrode the rebar if allowed to come in direct contact. The problem here is that the corrosion has a volume of 4 times the parent metal and hence tends to pop off the concrete cover due to this expansion. Theoretically epoxy coated rebar should prevent any corrosion regardless of concrete cover or quality on concrete. However, epoxy coated rebar has come under a lot of scrutiny lately. The Florida Dept. of Transportation conducted a study and found that even without signs of corrosion or physical damage the epoxy coating in some of their highway bridges was delaminating. Epoxy coated rebar is now band by several DOTs. Galvanizing is a great system for preventing corrosion of metals in general but has not performed well against chlorides. Galvanized rebar used to be popular for sewage treatment plants but resent studies in the 80's has shown that it is not as effective as was originally thought. If you are worried about corrosion there are additional steps you can take. Among these are a low water cement ratio (0.40 or less), increase cover to 3 inches, addition of a mineral additive such as fly ash, blast slag, or silica fume (silica fume is the best but added curing precautions exist), use a plasticizer (or super plasticizer) for good consolidation, and finally you could consider a corrosion inhibitor such as Calcium Nitrite (by W.R. Grace) or Rheocrete 222+ (by Master Builders). Moisture in the absents of either sulphates or chlorides should not effect the concrete paste or initiate corrosion of the rebar. Thomas Hunt ______________________________ Reply Separator _________________________________ Subject: [SEAOC] Epoxy Coated vs. Galvanized Rebars Author: seaoc::(SEAOCAB) at ~FABRIK Date: 6/6/96 9:45 AM From: seaoc(--nospam--at)power.net Date: Thu, Jun 6, 1996 9:45 AM Subject: [SEAOC] Epoxy Coated vs. Galvanized Rebars To: seaoc We have a condition where a flood-wall is to be constructed. The construction is going to last for a very long time. The foundation is exposed to saturated conditions. What are the advantages of epoxy coated vs galvanized rebars. Any information will be appreciated. thanks ahmed nisar - Dames & Moore San Francisco, CA ... ******* ***** * This email was sent to you via Structural Engineers Association of * California (SEAOC) email server. To subscribe (no fee) to the list, send * email to seaoc(--nospam--at)seaoc.org and in the subject of the message type * subscribe. To Unsubscribe, send email to seaoc(--nospam--at)seaoc.org and in * the subject of the message type Unsubscribe. For questions, send email * to seaoc-ad(--nospam--at)seaoc.org. Make sure you visit our web site at: * http://www.seaoc.org/seaoc ******** * ---------- Received: from touchstone.power.net by portia.fabrik.com with SMTP (Fabrik F05.4-000) id SINN.1801412(--nospam--at)portia.fabrik.com ; Thu, 6 Jun 1996 11:50:33 -0800 Received: by power.net (Smail126.96.36.199 #3) id m0uRj7V-000xEJC; Thu, 6 Jun 96 10:45 PDT Return-Path: <SFOAN(--nospam--at)AM.DAMES.COM> Received: from dmvax.dames.com by power.net with smtp (Smail188.8.131.52 #2) id m0uRj7S-000xEGC; Thu, 6 Jun 96 10:45 PDT Received: from MR.DAMES.COM by dames.com (PMDF V5.0-5 #11541) id <01I5L3EIFR8G8Y6MGJ(--nospam--at)dames.com> for seaoc(--nospam--at)power.net; Thu, 06 Jun 1996 10:45:07 -0700 (PDT) Received: with PMDF-MR; Thu, 06 Jun 1996 10:45:02 -0700 (PDT) MR-Received: by mta DMVAX.MUAS; Relayed; Thu, 06 Jun 1996 10:45:02 -0700 MR-Received: by mta DMVAX; Relayed; Thu, 06 Jun 1996 10:45:02 -0700 Disclose-recipients: prohibited Date: Thu, 06 Jun 1996 10:45:02 -0700 (PDT) From: "SFOAN (415) 243-3726" <SFOAN(--nospam--at)AM.DAMES.COM> To: seaoc(--nospam--at)power.net Message-id: <6702451006061996/A43109/DMVAX/11A632A92C00*@MHS> Autoforwarded: false MIME-version: 1.0 Content-type: TEXT/PLAIN; CHARSET=US-ASCII Content-transfer-encoding: 7BIT Importance: normal Priority: normal Sensitivity: Company-Confidential UA-content-id: 11A632A92C00 X400-MTS-identifier: [;6702451006061996/A43109/DMVAX] Hop-count: 1 Precedence: list X-Loop: seaoc(--nospam--at)power.net Subject: [SEAOC] Epoxy Coated vs. Galvanized Rebars Reply-To: seaoc(--nospam--at)power.net ---------- ...
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