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RE: Coring concrete slab

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Have you seen the Hilti FS 10 Ferroscan system?  It works on a magnetic
resonance concept and is designed specifically to map out rebar in
concrete.  One of the reasons for its development was to fit in the
niche between a Pacometer, which has limited capabilities, and X-Ray,
which is very expensive. Please contact myself or Brian Stocking (who is
local in L.A.)  if you would like more information.

Chris Gill
gillchr(--nospam--at)us.hilti.com
(800) 879-6000 x6913
0r stocbri(--nospam--at)us.hilti.com
(800) 879-6000 x7573

> ----------
> From: 	Tom Castle[SMTP:tcastle(--nospam--at)fwcse.com]
> Sent: 	Tuesday, March 10, 1998 4:28 PM
> To: 	'seaoc(--nospam--at)seaoc.org'
> Subject: 	Coring concrete slab
> 
>  Help!
> 
> 	I am working on a seismic retrofit of a group of residential
> timber framed buildings over a mild reinforced concrete parking flat
> slabs.  We are adding a lot (over 1,000) hold down rods through the
> deck.  Our plans show drilling through the 12 inch slab and placing a
> square plate washer on the underside of the slab.  The project is
> located in the City of Los Angeles.  I mention this fact because I
> believe this precludes the option of using epoxy anchors into the slab
> due to the low allowable values in the City and the relatively high
> loads (as much as 25,000# tension).  I specified on the plans to
> verify
> by nondestructive means the rebar location before drilling.  I did not
> want to cut any rebar because the slab appeared to need all it could
> get, specially with the new loads that could be imposed on it.  
> 
> 	The contractor "saved" the client $40,000.00 by deleting the
> pacometer tests to find the rebar.  He used a roto hammer to drill the
> holes and stopped if rebar was hit and moved the hole.  That was fun
> and
> it worked for the first couple hundred holes.  Then came a portion of
> the project located next to the electrical feed panels.  When the roto
> hamer hit them, the lights went out before the drilling could be
> stopped.  They tried the pacometer at this point but said that it
> would
> not detect the bottom bars or the bottom conduit.  
> 
> 	Their current thought now is to X-ray the slab at $120.00 per
> location at night (because no workers are allowed within a certain
> radius while the X-ray is working).  I have asked repeatedly if there
> was another method of nondestructive testing that could be employed.
> They say no.  I can't help but think in this day that someone has
> developed some device that could be used for this purpose that does
> not
> require the expense and inconvenience of the X-ray.  Has any one seen
> any thing?  It's really the contractor's problem, but it would make
> the
> job go alot easier if we could figure something out.  Thank you for
> any
> thoughts.
> 
> 
> 	Thomas Castle, S.E. 
> 
> 
> 
> 
>