Welcome to the The Garage Journal Board forums.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   The Garage Journal Board > The Garage > Flooring

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Search this Thread Display Modes
Old 05-24-2007, 08:28 AM   #1
cthomas
Junior Member
 
Join Date: Apr 2007
Location: Western NY
Posts: 4
Default Curing new concrete slab

Will be pouring new floor soon and I am looking for advice on "moist curing" (flooding garage for a week) vs. "membrane curing" with a cure and seal product. I don't want to apply a "cure and seal" product if I will have to later strip it and apply a more permanent sealer. Anyone here used a "cure and seal" product?
cthomas is offline   Reply With Quote
Old 05-24-2007, 08:45 AM   #2
Morrisman
Senior Member
 
Join Date: Nov 2006
Location: Angeles City, Philippines
Posts: 404
Default Re: Curing new concrete slab

Moist curing? Flooding? I've been told by many concrete 'experts' just to keep the surface damp if it is a real hot day, by laying sacking cloth on and keeping it damp with a light spray from a hose. I heard of the Romans curing concrete by putting it underwater, but as long as you have enough water available to ensure the chemical reaction completes properly I don't think you need to flood anything.

When I laid mine the concrete guy told me just to leave it open, as it was a cloudy winters day, no frost around, no sun. I covered it at night just in case we got heavy rain, which can take the cement out of the top 1/2" and make it powdery.
Morrisman is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 05-24-2007, 10:09 AM   #3
bmwpower
Super Moderator
 
bmwpower's Avatar
 
Join Date: Apr 2005
Location: NJ
Posts: 12,519
Send a message via AIM to bmwpower Send a message via Yahoo to bmwpower
Default Re: Curing new concrete slab

Yea, flooding would be for HUGE industrial sites where keeping a moist layer of burlap, etc. would be hard to do.
__________________
bmwcca 147895 | 99 m3 | 90 535i | 89 325is | 04 sienna le awd | 88 f250 4x4
my garage build | my wanted list
bmwpower is offline   Reply With Quote
Old 05-24-2007, 12:23 PM   #4
twostory
Senior Member
 
Join Date: Dec 2005
Location: Duluth, Georgia
Posts: 554
Default Re: Curing new concrete slab

My stem wall is 3.5 inches higher than the slab, so I just build a dam where the garage door is, and flooded the slab for 5 days. The dam leaked, but not very fast.

I did cover the slab in clear plastic to keep the evaporation down. I also ran a hose under the plastic 24/7, but since I used plastic, the water flow rate was not very large. I probably used 2,000 gallons of water to keep it wet for 5 days.
twostory is offline   Reply With Quote
Old 05-25-2007, 02:03 PM   #5
Morrisman
Senior Member
 
Join Date: Nov 2006
Location: Angeles City, Philippines
Posts: 404
Default Re: Curing new concrete slab

Quote:
Originally Posted by twostory View Post
My stem wall is 3.5 inches higher than the slab, so I just build a dam where the garage door is, and flooded the slab for 5 days. The dam leaked, but not very fast.

I did cover the slab in clear plastic to keep the evaporation down. I also ran a hose under the plastic 24/7, but since I used plastic, the water flow rate was not very large. I probably used 2,000 gallons of water to keep it wet for 5 days.
2000 gallons of water? Bejesus, I thought you to merely keep it wet enough for the chemisty to go down.

What is to be gained by this underwater world of concrete?
Morrisman is offline   Reply With Quote
Old 05-25-2007, 02:31 PM   #6
john56h
Member
 
Join Date: May 2007
Location: Hudson Valley, NY
Posts: 64
Default Re: Curing new concrete slab

The longer it takes for the concrete to harden...the more strength it will have.
john56h is offline   Reply With Quote
Old 05-25-2007, 04:10 PM   #7
PAToyota
Senior Member
 
PAToyota's Avatar
 
Join Date: Jan 2006
Location: South Central Pennsylvania, USA
Posts: 4,088
Send a message via AIM to PAToyota
Default Re: Curing new concrete slab

It really doesn't need to be flooded. And running water can actually wash away the lime and cement from the top surface - especially if a stream of water is hitting the surface. Light mist of water across burlap or under plastic is enough to keep it damp. You just don't want it to dry out completely at any point or the reaction stops. After three days it has reached 30% of its theoretical strength, 60% after seven days, and 98% after 28 days. Which is what kills me when someone specifies 4500psi concrete and lets it dry out in the first day...
PAToyota is offline   Reply With Quote
Old 05-25-2007, 09:34 PM   #8
rt66jt
Member
 
Join Date: Aug 2006
Location: York, PA
Posts: 42
Default Re: Curing new concrete slab

Quote:
Originally Posted by cthomas View Post
Will be pouring new floor soon and I am looking for advice on "moist curing" (flooding garage for a week) vs. "membrane curing" with a cure and seal product. I don't want to apply a "cure and seal" product if I will have to later strip it and apply a more permanent sealer. Anyone here used a "cure and seal" product?
Cure and seal products are as permanent as any sealer. You will not need to strip it unless you opt for epoxy, paint or similar.
rt66jt is offline   Reply With Quote
Old 05-26-2007, 09:54 AM   #9
john56h
Member
 
Join Date: May 2007
Location: Hudson Valley, NY
Posts: 64
Default Re: Curing new concrete slab

Quote:
Originally Posted by PAToyota View Post
It really doesn't need to be flooded. And running water can actually wash away the lime and cement from the top surface - especially if a stream of water is hitting the surface. Light mist of water across burlap or under plastic is enough to keep it damp. You just don't want it to dry out completely at any point or the reaction stops. After three days it has reached 30% of its theoretical strength, 60% after seven days, and 98% after 28 days. Which is what kills me when someone specifies 4500psi concrete and lets it dry out in the first day...

The number of days compared to strength of concrete is not in reference to how many days it was kept moist during curing. It is a base-line of stregnth versus cure time. On large projects there are test samples taken during the pour (usually four test cylinders). The test cylinders are brought to a laboratory where they are broken in a press which measures the specific amount of force in PSI that it requires to break.

The first cylinder is broken after 7 days...if it breaks within 60% of the design strength (2700 PSI for a 4500 design mix) then the engineers are comfortable that the pour was successful. A second cylinder is broken at 14 days and a third at 28 days. The strength should be very close to 4500 PSI at 28 days, but if it isn't...often the fourth cylinder will be broken at a later date to determine if the strength has been achieved after an extended curing period.

Usually the same testing laboratory that is on site for collection of cylinders will also test for temperature, air entrainment and slump. The tests are taken for each truck load of concrete. On large projects there will be many test cylinders since four are taken from each load.
john56h is offline   Reply With Quote
Old 05-26-2007, 12:57 PM   #10
Morrisman
Senior Member
 
Join Date: Nov 2006
Location: Angeles City, Philippines
Posts: 404
Default Re: Curing new concrete slab

Quote:
Originally Posted by john56h View Post
The longer it takes for the concrete to harden...the more strength it will have.
True, but concrete hardens, not dries out. It is not like water based paint where something evaporates. Concrete is a chemical reaction, involving heat, and water activates it. Correct, if you let it go dry in the sun the chemical reaction won't finish properly, but keeping it immersed in water is no better than just keeping the surface damp, just a lot more work.
Morrisman is offline   Reply With Quote
Old 05-26-2007, 05:21 PM   #11
PAToyota
Senior Member
 
PAToyota's Avatar
 
Join Date: Jan 2006
Location: South Central Pennsylvania, USA
Posts: 4,088
Send a message via AIM to PAToyota
Default Re: Curing new concrete slab

Quote:
Originally Posted by john56h View Post
The number of days compared to strength of concrete is not in reference to how many days it was kept moist during curing. It is a base-line of stregnth versus cure time.0
Quote:
Originally Posted by Morrisman View Post
True, but concrete hardens, not dries out. It is not like water based paint where something evaporates. Concrete is a chemical reaction, involving heat, and water activates it. Correct, if you let it go dry in the sun the chemical reaction won't finish properly, but keeping it immersed in water is no better than just keeping the surface damp, just a lot more work.
What Morrisman is saying is what I was trying to get across - you don't have to flood it. The point that John misses is that the chemical reaction stops when it dries out. So if it is dry before seven days or twenty-eight days it isn't going to reach that ultimate strength as if it is kept most for the full twenty-eight days to let the reaction run its complete course.
PAToyota is offline   Reply With Quote
Old 05-29-2007, 09:34 PM   #12
V-10 Killer
Senior Member
 
V-10 Killer's Avatar
 
Join Date: Feb 2007
Location: Midland, MI
Posts: 968
Default Re: Curing new concrete slab

Ok, here's a curveball. What about a garage slab thats poured after the garage is framed and roofed? You can keep it damp, at risk of introducing extra water into the lumber, but minimal to no sun to activate it.
__________________
www.V10Killer.com
My Toybox Build

"Up until the 20th century, advancement of civilization was defined by the strongest among us.
Now, it appears its going to be defined by the weakest among us."
V-10 Killer is offline   Reply With Quote
Old 05-29-2007, 10:17 PM   #13
Uncle Buck
Banned
 
Join Date: Mar 2005
Location: Kansas
Posts: 9,120
Default Re: Curing new concrete slab

It does not need any sun to cure, end of problem!

One more interesting note regarding concrete is that the ultimate strength of the concrete is not attained for some insane amount of time like A YEAR or perhaps more. Yes, I said a year. Being honest I do not recall the exact amount of time, but it is a fact that concrete continues to harden, many times long after a slab is poured or a structure is built. I do not claim to be an expert, but that was one of the trivial bits I recall being told when I used to work for a batch plant (not hands on, middle management).

I am looking for no arguement, I am simply sharing what they told me.

Last edited by Uncle Buck; 05-29-2007 at 10:40 PM.
Uncle Buck is offline   Reply With Quote
Old 05-30-2007, 05:21 AM   #14
PAToyota
Senior Member
 
PAToyota's Avatar
 
Join Date: Jan 2006
Location: South Central Pennsylvania, USA
Posts: 4,088
Send a message via AIM to PAToyota
Default Re: Curing new concrete slab

V10: That is exactly the way mine was done - the whole structure was framed, sided, and under roof before the slab went in. Goes a long way towards being able to let the slab cure on its own schedule.

Hholmberg: You'll notice my post above says 98% at 28 days. People ask why they don't just say 100% at 35 days or something. As you say, it is because that last little bit takes months if not a year or more!
PAToyota is offline   Reply With Quote
Old 05-30-2007, 04:06 PM   #15
V-10 Killer
Senior Member
 
V-10 Killer's Avatar
 
Join Date: Feb 2007
Location: Midland, MI
Posts: 968
Default Re: Curing new concrete slab

I remember watching a special on the construction of the Hoover dam. They mentioned that the concrete would have taken a few hundred years to cure if just left there. So they installed refrigeration tubing or something in the concrete while they were pouring. Once they felt it was cured sufficiently, they filled the tubing with concrete too.
Yeah, curing is like an exponential function on a graph, it might never be 100%, but at some point we call it that for simplicity sake.
__________________
www.V10Killer.com
My Toybox Build

"Up until the 20th century, advancement of civilization was defined by the strongest among us.
Now, it appears its going to be defined by the weakest among us."
V-10 Killer is offline   Reply With Quote
Old 09-06-2007, 07:29 PM   #16
kutza
Member
 
kutza's Avatar
 
Join Date: Nov 2006
Location: Yorktown VA
Posts: 51
Default Re: Curing new concrete slab

okay, We poured our 30x30 6in avg. depth monolithic slap today.
I have watered it don to a damp top a few times until night time.
What shall I plan on doing with it next few days? Hose it down all over. Let the surface semi (patchs) dry, hose it off again? endless cycle! I just spent my vacation and a lot of money on this, I just want it to cure right.
thanks.
__________________
I know I cant spell!
kutza is offline   Reply With Quote
Old 09-06-2007, 08:09 PM   #17
Junkman
Senior Member
 
Junkman's Avatar
 
Join Date: Dec 2006
Location: Northeastern CT
Posts: 5,029
Default Re: Curing new concrete slab

cover with burlap and keep it wet at all times. Do not allow it to dry out even for an hour....
__________________
Philosopher Emeritus Of Garage Journal

Men wake up as good-looking as they went to bed.
Women somehow deteriorate during the night.

Never argue with an idiot. He'll drag you down to his level, then beat you with experience.
Junkman is offline   Reply With Quote
Old 09-07-2007, 08:01 PM   #18
z28toz06
Senior Member
 
z28toz06's Avatar
 
Join Date: Nov 2005
Location: Connecticut
Posts: 1,009
Default Re: Curing new concrete slab

I have mixed by hand and poured foundations for telecommunications equipment. My uncle and father were both wire lathers in New York City for 30 years. A friend of mine pours concrete for a living and just did my 24 x 32 foot garage. No one has ever made that big a deal out of it. Freezing was the worst thing that was ever worried about.

I am not an expert but know several and have never heard of watering concrete to this excess. There is a chemical reaction heat process going on, I understand that but to cure concrete is to let it dry out. What are we talking about strength wise here? Are you guys parking sherman tanks in your shops that you're worrying about this? I plan on putting a lift in mone and I have 4000 pound concrete poured and 4" deep. I have no worries what so ever about it's strength. This sounds like over kill to a non existing problem.
z28toz06 is offline   Reply With Quote
Old 09-07-2007, 08:30 PM   #19
SCOOTER
Senior Member
 
Join Date: Mar 2006
Location: Washington
Posts: 226
Default Re: Curing new concrete slab

I put a sprinkler on mine the morning after the pour 7am ( finished @ 1am) the the next two days it rained a little and on that third day I saw cut it...done end of story cured and not worring about it...
__________________
Start drinking till you see double and act single

I'm not a true BADASS....But i do play one on the Internet..

YAAA It's a HYBRID...It burns both...GAS AND RUBBER


www.brokebastardsoffroad.com
SCOOTER is offline   Reply With Quote
Old 09-07-2007, 09:45 PM   #20
kutza
Member
 
kutza's Avatar
 
Join Date: Nov 2006
Location: Yorktown VA
Posts: 51
Default Re: Curing new concrete slab

z28toz06 & Scooter
Thanks for helping me relax on this topic. I kept is water down, but not all day long. Anyways Over Worring, and Over annalyzing is why I am here!
thanks to all.
__________________
I know I cant spell!
kutza is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 05:09 AM.