Need a book? Engineering books recommendations...

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

RE: Concrete curing

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Craig,

In my experience nothing compares to saturated water curing. (ponding,
burlap or the like), and yes it tends to be overlooked. Having spent 5 years
in Perth, Australia where it is routinely over 30 degC (and often 40)for 8
months of the year with about 5% RH, curing is of utmost importance. But
even there contractors take short cuts (surprise, surprise) and use curing
compounds to try and reduce the curing time. It seems to be unsecessful more
ofter than not, particlary in the extreme hot weather. Plastic shrinkage
cracking is a common occurance, espicially with SOG's.

Now having moved to the cooler (and wetter) climate of Vancouver I find it
much less of a problem. (Not the absence of curing, that's still prevalent,
but it doesn't cause so many problems). I still hammer the contractors on
every job I do to ensure adequate curing, after that it's up the them. The
most common method here seems to be sprinklers and/or burlap, but I may be
wrong, I havn't been here that long.

On a side note, many 'old timers' I spoke to in Australia seem to mention a
common theme wrt cracking, in that it was occurring much earlier than in
years gone by. More often than not, shrinkage cracking was occuring within
the first 2 days in recent times whereas these older guys recall that
shrinkage cracking wasn't a problem until about a week after the pour. One
suspect is the cement manufactures are grinding the cement to much finer
particles, thus increasing the water demand for the same wc ratio. Any
thoughts/comments on this.

derek

-----Original Message-----
From: Craig & April [mailto:csmleko(--nospam--at)bellsouth.net]
Sent: Wednesday, June 30, 2004 1601
To: seaint(--nospam--at)seaint.org
Subject: Concrete curing


Anyone with thoughts regarding concrete curing, or lack thereof in today's
building industry? ACI specifies 7 days in "moist" condition unless high
early strength concrete or accelerated curing is used. In S. Florida I find
this requirement to be often if not mostly ignored by both engineers and
contractors alike with respect to residential SOGs and even elevated
structural slabs...unless 90% outdoor humidity qualifies as a "moist
condition." Curing compounds are often avoided because they interfere with
tile mortar bond and it seems that plastic, burlap or sprinklers are too
much trouble. What are the current practices in other parts of the country?
I'm guessing that dryer climates make this much more of an issue.

Craig


******* ****** ******* ******** ******* ******* ******* ***
*   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 
******* ****** ****** ****** ******* ****** ****** ********