Need a book? Engineering books recommendations...

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

Re: Cold Weather Reinf. Masonry

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Dave,

First a question, in what code/spec are you referring to section 2.3.2.2?

The current MSJC (2005 masonry code & spec) does provide some requirements
in section 1.8 C.  I believe this would be either the same or very
similar for the 2002 MSJC, but I cannot confirm it at the moment as I
cannot locate my 2002 edition.  The one that you likely would be most
interested in section 1.8 C.4.e.  It states:

"20 deg F (-6.7 deg C) and below:  Maintain newly constructed masonry
temperature above 32 deg F (0 deg C) for at least 24 hr after being
completed by using heated enclosures, electric heating blankets, infared
lamps, or other acceptable methods.  Extend time to 48 hr for grouted
masonry, unless the only cement in the grout is Type III portland cement."

The thing to remember is that even though CMU is "basically" concrete, it
does act a little differently during curing.  For concrete, the free water
is basically only lost by hydration and evaporation.  For CMU, on the
other hand, free water in the mortar and grout is also lost by absorption
into the CMU in addition to the hydration and evaporation.  Thus, the free
water will tend to "go away" much quicker and in general CMU is a little
bit better able to handle cold weather quicker.  This assuming that you
heated the CMU (both in place and those yet to be placed) properly during
construction and protect the in place CMU for an appropriate amount of
time after it is in place.

In the end, you HAVE to follow the spec cold weather sections of the MSJC
(assuming that the MSJC is the "law of the land" where you are).  You can
certainly demand or request that something above and beyond be used, but I
would suggest that you consult with the masonry contractor first before
just demanding, especially if that contractor is rather experienced.  I
would assume that most masonry contractors in your area are fairly used to
working in "frozen tundra" like conditions as they exist there every year!

Regards,

Scott
Adrian, MI


On Wed, 14 Dec 2005, Nuttall, Davin J. wrote:

> List,
>
> I was wondering what the other engineers here on this list do regarding the installation of cold weather reinforced masonry?
>
> I am familiar with tenting, temporary heating, and specification section 2.3.2.2.
>
> My concern is for those REALLY COLD spells of time (around -10 to +10 degrees) when I feel heating the tented area for only 24 hours after construction does not seem all that long.  Are the grouted cells in a 12" block, and mortar joints really hydrated enough after just 24 hours, so the site can then freeze solid over a weekend or holiday?
>
> Am I overly concerned, or do others require additional time with the tented heat for the grouted cells to cure?
>
> TIA
>
> Dave Nuttall, P.E.
> Green Bay, WI
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> *
> *   This email was sent to you via Structural Engineers
> *   Association of Southern California (SEAOSC) server. To
> *   subscribe (no fee) or UnSubscribe, please go to:
> *
> *   http://www.seaint.org/sealist1.asp
> *
> *   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
> *   send to the list is public domain and may be re-posted
> *   without your permission. Make sure you visit our web
> *   site at: http://www.seaint.org
> ******* ****** ****** ****** ******* ****** ****** ********
>
>

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********