#1  
Old 10-08-2010, 06:55 PM
Apprentice
 
Join Date: Jun 2009
Location: Westchester
Posts: 106
Default curing hearth slab in lower temps

I'm going to frame my hearth slab this weekend, and pour it next weekend, I hope. How long will it take to cure? We should get just about a week of nights above 40 or so (just north of NYC). Is this enough time? If it dips a bit below that, will a worklight under the slab at night keep it warm enough?
Reply With Quote
  #2  
Old 10-09-2010, 04:41 AM
dmun's Avatar
Moderator
 
Join Date: Jul 2005
Location: New Jersey USA
Posts: 4,216
Default Re: curing hearth slab in lower temps

40f seems to be the magic number. You may cover it with a tarp and leave a light bulb burning underneath at night. You absolutely don't want anything near freezing.
__________________
My geodesic oven project:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #3  
Old 10-09-2010, 07:08 AM
Tscarborough's Avatar
Il Pizzaiolo
 
Join Date: Oct 2009
Location: Ausitn
Posts: 2,998
Default Re: curing hearth slab in lower temps

Once there is no free water in the concrete (it has "set"), then freezing can't hurt it. It WILL retard the cure, though not stop it. A tarp and shop light will speed up the cure.
Reply With Quote
  #4  
Old 10-10-2010, 01:38 PM
Serf
 
Join Date: Jan 2010
Location: NYC
Posts: 23
Default Re: curing hearth slab in lower temps

If the temperature goes below 40 F the concrete will stop curing. It is advisable to cover the concrete with a thick layer of straws or some kind of insulating blanket for at least a week, if ambient temperature are forecasted to drop below 40F.
Reply With Quote
  #5  
Old 10-25-2010, 10:50 AM
SteveP's Avatar
Apprentice
 
Join Date: Oct 2008
Location: Port Saint Lucie, FL
Posts: 114
Default Re: curing hearth slab in lower temps

As a general rule, the concrete should not be allowed to get below 50F. As T stated, when concrete gets close to freezing, hydration will practically stop and the slab will not gain any strength. You will get some heat in your mix due to the exothermic reaction, but I don't think it will be enough to overcome the cold temperatures. You could end up with a weak "green" slab if it gets too cold. If you could put a tarp around it with a heater or a heavy duty shop light, this will probably work. On a side note, I poured a 3' x 3' x 3' foundation when it was <50F outside and the concrete was still green and brittle after 24 hours.
__________________
My WFO project:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
2 x 4's inside the hearth slab masuzzu Tools, Tips and Techniques 1 10-19-2008 08:49 AM
Will the bottom of the hearth slab get hot? DrakeRemoray Getting Started 2 04-12-2006 11:17 AM
Between Hearth SLAB and Hearth BRICKS, slip plane. Marcel Newbie Forum 2 09-12-2005 05:35 PM
How far to cantilever the Hearth Slab? Marcel Getting Started 2 08-31-2005 09:38 AM
Spanning the wood storage below the Hearth slab. Marcel Getting Started 0 08-22-2005 09:13 PM


All times are GMT -7. The time now is 02:51 AM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
2006/10 Forno Bravo, LLC