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Re: Bar Placement in Slab with Laser Screed

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How about lap splicing the bars in one direction every 20 feet?  Then each section of bars could be chaired up after the screed has passed by.

Jason Emoto


>>> "Rich Lewis" <sea(--nospam--at)lewisengineering.com> 03/31/05 07:56AM >>>
I was watching the tail end of the pour of a slab on ground this morning and
was discouraged with the placement of steel.  What was supposed to be top
bars in the slab for shrinkage control ended up as middle or bottom bars.
The bars were up on chairs, but the placement method pushed them down.

 

The slab was screeded with a laser screed.  It's called a 240 screed because
it is 12 ft. wide and has a 20 ft. reach, making 240 sf per pass.  The
screed pulls the concrete towards itself.  The tires on the screed push the
rebar and any chairs down into the ground.  So when the concrete is pulled
up to the screed it is holding down the rebar.  Now when they move the
screed they attempt to pull the bars up, but in a 6-8" thick slab you can't
pull bars up from the bottom to the top.  It is impossible.

 

Isn't there some method to use the laser screed and still get top bars?  I
asked the operator and he said this is how it is done all the time.  I'm
wondering why hasn't this been perfected yet?  If it was truly critical that
I get top bars for a strength reason there is no way I could count on it.

 

Has anybody developed a placement specification and method to cover this
situation?

 

Rich Lewis

Lewis Engineering

 

 



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