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RE: Mortar Testing

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Scott -

Sorry, I was referring to questioning what goes on in the field, quality of
field tests (or lack thereof) and inspections (or lack thereof).

What WAS interesting in my "experience" was the prism tests. I had
originally designed for F'm =3,000 psi. I knew that 3,750 psi block was
readily available and that, along with 2,500 psi grout would get me F'm =
2,500 psi (based on Tbl 21-D of the UBC/CBC). I needed a little more than
that (3,000 psi), so I specified 4,000 psi grout, fairly sure that the
combination of 3,750 psi block and 4,000 psi grout would get me F'm = 3,000
psi. I also specified 3,000 psi mortar, but didn't get tests on that (even
though I asked for them - now I know why from this thread). I did get Type M
mortar with a specified minimum strength of 2,500 psi and a sample break of
7,500 psi (!) from a previous (2003), lab controlled test.

Anyway, when the prisms were cut from the wall (including face shell, grout
and joints), using normal strength block (compressive strength of 1,800
psi), all of the tests but two (10 out of 12) came back in excess of 3,000
psi. The averages on two of the buildings were over 3,000 psi and the one
that wasn't was something like 2,960 psi which I called "close enough". One
of the reasons is the grout tested at 5,500 psi (!) average. I can only
imagine what 3,750 psi block and 4,000 psi grout would have produced. I wish
I would have cause to ask for the remaining half of the 3rd building (the
only one getting the 3,750 psi block) to be tested just to satisfy my

You can see photos, including the port holes where the prisms were cut, at:


T. William (Bill) Allen, S.E. (CA #2607)	
Consulting Structural Engineers	
V (949) 248-8588	 .	 F (949) 209-2509	

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)] 
Sent: Tuesday, April 05, 2005 4:05 PM
To: seaint(--nospam--at)
Subject: RE: Mortar Testing


Hey, questioning it good.  It keeps you on your toes and always learning.


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