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Re: Perform A Chain Drag Study?

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	This is done a lot for parking structures in Canada where salt is used
to remove snow.  The chlorides penetrate the concrete and cause the
reinforcing (normally the top steel) to corrode.  This corrosion causes
the reinforcing to "grow" like a tree root resulting in horizontal
splitting or delimitation of the slab concrete.

	Strange as it may seem, you can locate this delimitation by simply
dragging a chain around and listening.  You can't miss it; there is as
much difference between the sounds of delamination and solid concrete as
between tapping on a guitar vs. tapping on a meat block.  A piece of
chain six feet long weighing 8 to 12 pounds should do nicely but a
lighter chain will also work.

	Good luck.


				H. D. Richardson

> Hyndman, Keith wrote:
> I've been asked to evaluate an Existing Concrete Parking Garage.  Part
> of the study is to check wear on the parking surface using a Chain
> Drag Study.  Anybody know waht that is, how you do it, limiting
> criteria, etc?
> Thank you,
> Keith Hyndman
> Exton, PA