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RE: FRP rebar in concrete design

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>I would suggest caution in using FRP "rebar" in salt exposed areas.
> ... The FRP "rebar" decomposed nearly  completely in the wet/dry
> zone after 6 months of a sinle  wet/dry cycle per day. 

My own experience in a different area follows this. I got involved in a 
number of instances of sudden rupture of glass-epoxy compressed natural 
gas tanks. The tanks operated at 3000 psi and were mounted underneath 
vehicles with engines modified to use natural gas. The ruptures occurred 
at pressures well below the working pressure. Given that the verified 
burst pressure for new vessels was about 12000 psi, the strength of the 
tanks had decreased considerably in service. There was some squabbling 
about the source, but it was clear that the glass wrapping had undergone 
some sort of environmental attack, and had been exposed to moisture and 
either road salt or salt vapor. NASA tests also showed degradation of 
exposed (outdoors near Cleveland, but not on roads) tanks especially when 
subject to cyclic loading.  

No question it works for boats and Corvettes and I've seen it adopted to 
storage tanks and barge covers but I'm a little leery of FRP as the 
structural magic bullet.


Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw