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From: "seaoc(--nospam--at)seaoc.org" <seaoc(--nospam--at)seaoc.org> at -FABRIK/Internet
Date: 3/26/97 1:51PM
To: Tom Hunt at FDIV-06
*To: "seaoc" <seaoc(--nospam--at)seaoc.org> at -FABRIK/Internet
Subject: Re: Corrosion Inhibitors
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        Juan,
        
        If your known corrosion is very localized then you can chip out 
        the concrete, sand blast the reinforcing, and then use a 
        suitable patching material (Contact Sika, they have lots 
        patching products).
        
        Considering that you are sitting in saltwater and your corrosion 
        problem is probably systematic then your only hope at this point 
        is probably a cathodic protection system.  If you (or your 
        client) have the money you can hire a concrete/corrosion 
        specialist who can map out the walls using, for example, ASTM 
        C876 "Half-Cell Potentials of Uncoated Reinforcing Steel in 
        Concrete" methods.  This is an electrical test for determining 
        corrosion activity of reinforcing steel.  What you get is an 
        equipontential mapping of corrosion activity that looks like a 
        topo contour map.
        
        The normal cathodic protection system will consist of what looks 
        like wire mesh or chicken wire (such as DSA anode mesh by ELTECH 
        Systems or Ferex anode mesh by Raychem Corp) that is placed 
        against the wall and then grouted in with a topping layer (it is 
        actually a little more complicated than this).  The system is 
        then hooked up to an A.C. to D.C. converter with automatic 
        control circuitry.
        
        This type of system should be designed by a corrosion specialist 
        with experience in your particular application and who is 
        familiar with the conditions in your area.  To design an 
        appropriate system they will need to determine the electrical 
        continuity of the rebar, chloride content of the concrete, depth 
        of rebar from the surface, physical structure limitations, A.C. 
        power availability, rebar current density, etc.
        
        For more background (and all the correct buss words) look at the 
        NACE (National Association of Corrosion Engineers) publications. 
        They can be reached at 713-492-0535.  Their publications cover 
        concrete linings, cathodic protection, effects of concrete mix 
        components, and there was even a NACE Paper No. 325 presented at 
        their "Corrosion 96" conference on "Coating Disbondment in 
        Epoxy-Coated Reinforcing Steel in Concrete" (A summary of the 
        Florida DOT-USF experience with coating disbondment of 
        epoxy-coated rebar!?!).
        
        Thomas Hunt
        Fluor Daniel
        
        *********************************************************

I have just completed a project in which we built basements in 
reinforced concrete to house machinery in a steel mill. The soil 
surrounding these has a high phreatic water level, and the water is 
saltwater. This project is located about 15 miles from the seashore. Now 
we have found evidence of corrosion in the reinforcement; does anyone 
have any experience on how to treat this problem?
     
Any answer will be greatly appreciated.
     
Juan C. Gray
     



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From: "Hunt, Tom" <tom.hunt(--nospam--at)fluordaniel.com>
Subject: Re:Corrosion Inhibitors
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