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RE: CMU California Practice in the 1950's

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CMU construction practice and the CMU open end unit availabilty are a function of region and time period.  The US Army Corps of Engineers had a lot to do with pushing the open end units.   
The A blocks (one end open) are not very difficult to find anywhere in the US.  The masonry contractors like them in the field because if the rebar spacing of 16" or more, you can have one lap splice at the dowel and let the vertical bar extend up to the top of the wall.  The block is then placed around the bar as opposed to up and over, or with a lot of lap splices. 
Once the contractors are accustomed to using the A blocks, they prefer them.  There are a lot of good details that the Corps has in their Std. Det. No. 00-90-04.

Regards, Harold Sprague


Subject: RE: CMU California Practice in the 1950's
Date: Mon, 27 Apr 2009 07:30:55 -0700
From: rgarner(--nospam--at)
To: seaint(--nospam--at)

Correct me if I'm wrong, but I first saw the open-ended units in the '70s.  They weren't popular at first since the units tended to be somewhat warped and lent a basket-weave appearance to the finished wall - we used to call it basket-weave bond instead of running bond.


We used to grout only the reinforced cells back then.  This was back when grout was expensive and labor was cheap.  Ahh, the good old days.


Bob Garner (At the time, working in Oakland, San Jose and Santa Cruz, CA)


From: Bill Allen [mailto:t.w.allen(--nospam--at)]
Sent: Sunday, April 26, 2009 12:48 PM
To: seaint(--nospam--at)
Subject: RE: CMU California Practice in the 1950's




I know the preference for open end blocks which means grouted cells are really grouted double cells, but I'm curious if this is true.


After all, grouting solid is a heavier wall producing more force at the tie at the top and increasing the load on the diaphragm. If bars are only required at 48" (#4 @ 24" or even #5 @ 32"), that means half the wall can be un-grouted providing quite a bit of reduction in mass transferred to the roof diaphragm.


I've designed quite a few block walls grouted at steel only, all of them since 1980. I'm wondering if I'm out of step with standard practice. Of course, it wouldn't be the first time.


T. William (Bill) Allen, S.E.


Consulting Structural Engineers
V (949) 248-8588 F(949) 209-2509

I know that it has been the general practice in California to grout CMU walls solid since at least the 1980's. 

Regards, Harold Sprague

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