Return to index: [Subject] [Thread] [Date] [Author]

Re: Dowelling a URM infill

[Subject Prev][Subject Next][Thread Prev][Thread Next]
A suggested retrofit detail for an existing Infill in a URM wall:

Install 3/4" diameter all-thread pins in pairs embedded in epoxy adhesive in 
1" diameter holes, the pins of a pair a few inches apart installed at an 
angle of about 30 degrees to the surface of the wall so that the pins form a 
cross at the center of the wall at the infill/wall intersection plane.  

On the other hand, I've designed CMU infills into URM walls without pins [but 
not in Santa Ana].  In that detail, bricks are removed from an interior wythe 
at the jambs and sill at about 16" to 24" spacing.  The Infill is constructed 
with open-ended blocks open to the jambs.  Grout placed into the open end 
cells flows into the voids left by the removed brick to form grout keys.  
Pre-hydrated mortar is used to fill the gap between the top of the infill and 
the head of the opening.  For a 10x10 opening, I'd probably set pins into the 
head, but may not if the opening is narrower.  I believe that the grout keys 
are more effective than dowels because they are more rigid.  I specify for 
the grout an aluminum powder admixture such as Sika Grout-Aid or PMP Grout 
Additive from E-Z Mix.  The admixture produces slight expansion of the grout 
in the plastic state to compensate for the plastic shrinkage that would 
otherwise tend to form a separation between the brick and the grout as it 
cures.  It is important to saturate the brick before grout placement because 
brickwork has a high affinity for water and may dry the grout before it 
cures, producing poor-quality keys.  Could that kind of detail have been done 
on your project?

Nels Roselund
Structural Engineer