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RE: Filling Holes in CMU

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Nels -

Thanks for the response. The purpose of filling the holes is that the holes
will be cut to perform prism tests on new construction because the
contractor did not follow the plans (not his fault - bid and built off of
preliminary plans provided by owner) and the strength is suspect.

Soooo...right now there is no load on the wall, but the design load will be
significant. The walls were designed as slender walls and the basis of the
design was a F'm of 3,000 psi. I specified a 4,000 psi grout and 3,000 psi
type M mortar. I *think* both of those elements were provided (documents are
"in the mail"), but they used standard strength block (compressive strength
of 1,800 psi) instead of high stress block (compressive strength of 3,750
psi).

Appearance isn't important. The exterior will be plastered; the interior
will be drywalled.

The only thing that matters is achieving the design capacity and everyone on
the team is "on board" with that concept (even though the contractor
originally thought cores were adequate for the prism test).

Hopefully, that clarifies the problem.

Regards,
	
T. William (Bill) Allen, S.E. (CA #2607)	
ALLEN DESIGNS	
Consulting Structural Engineers	
http://www.AllenDesigns.com	
V (949) 248-8588	 .	 F (949) 209-2509	
||-----Original Message-----
||From: Nels Roselund [mailto:njineer(--nospam--at)att.net]
||Sent: Thursday, January 20, 2005 11:27 AM
||To: seaint(--nospam--at)seaint.org
||Subject: RE: Filling Holes in CMU
||
||Bill,
||
||Do the holes result in the wall having less than the required capacity?
||If
||not, I would fill them in some simple way: fill them with common bricks
||and
||mortar; or, if appearance is important, with CMU face-shells set in
||mortar.
||If the holes must be filled to restore strength, it probably will not be
||practical to try to leave the fill in the same state of stress as the
||adjacent masonry -- it will be unstressed when the fill is completed,
||while
||the adjacent masonry will be carrying the load that was once in the
||cut-outs.  If that's O.K., I'd probably fill the hole with brick and
||mortar,
||and dry-pack mortar into the top bed joint on a subsequent day, after the
||setting mortar had attained most of its shrinkage.  Or make the mortar
||with
||Eisenwall Cement by CTS [8oo-929-3030 in Orange County CA]: it's a
||shrinkage-compensated cement.  If appearance is important, I'd use an
||H-shaped CMU, and inject a fine grout with Sika GroutAid to control
||shrinkage, or make it with  Eisenwall Cement.
||
||I'd avoid epoxy grout -- its messy, and it gets very hot in large masses,
||and has a relatively low elastic modulus.
||
||Nels Roselund, SE
||South San Gabriel, CA
||njineer(--nospam--at)att.net
||
||-----Original Message-----
||From: Bill Allen, S.E. [mailto:T.W.Allen(--nospam--at)cox.net]
||Sent: Wednesday, January 19, 2005 2:59 PM
||To: seaint(--nospam--at)seaint.org
||Subject: Filling Holes in CMU
||
||I've got a project where I have to have prism samples cut from existing
||CMU
||walls.
||
||These holes will be somewhere between 16" square to 8" wide x 16" high.
||
||I'm looking for recommendations on what I should fill the hole with and
||any
||material/procedural specific recommendations that can be made.
||
||I'm thinking that it will require some sort of a bonding agent (Sika or
||??)
||and then the hole filled with a non-shrink epoxy grout in a hole formed by
||plywood attached to the adjacent CMU and a fill tube at the top.
||
||Maybe this isn't the right/best way to go. I would like to hear
||alternatives.
||
||Even if this is the right/best way to go, I would be interested in
||recommendations for the bonding agent and epoxy grout.
||
||The design F'm is 3,000 psi using high strength block (compressive
||strength
||of 3,750 psi), 4,000 psi grout and 3,000 psi type M mortar.
||
||For more info on the project, go to:
||http://www.allendesigns.com/projects/20402/20402.htm
||
||Thanks,
||
||T. William (Bill) Allen, S.E. (CA #2607)
||ALLEN DESIGNS
||Consulting Structural Engineers
||http://www.AllenDesigns.com
||V (949) 248-8588	 .	 F (949) 209-2509
||
||
||
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