Concrete drying time / fan question

[CheckeredFlag]

I have an older concrete floor in my Mid Michigan garage - and I'm planning to try and resurface it myself this Summer.

I've read other threads here and watched some YouTube videos on how to do it, but here's my question:

Can you use an Air moving fan to kinda help speed the drying time up, or would that cause some kind of premature curing problem ?

I have a one car wide / roughly one and a half car deep sized garage (I can get the dimensions if it really makes a difference.)

What I'm trying to accomplish is- get the project done first thing in the morning, and be able to move things back in at the very end of the day ...

or, for those that have done it already- do you normally need a longer curing time ?

Starting to research some now for a few warmer weather projects

First time (obviously) trying this

TIA

 

[Peoria Man]

I wouldn't bother with the fan. Concrete cures best (IE, hardest) when its kept in a moist condition. And in extreme cases, such as when the subgrade materials are wet and the concrete is exposed to heat and wind, the slab can curl. Enough that you'd ever notice? No, but you don't want to make matters worse by making it dry prematurely.

 

[CheckeredFlag]

thanks !

 

[CheckeredFlag]

so how long sure I let it cure before moving things back on there, or parking a car in there again ?

 

[alky]

I have seen tire tracks across a driveway that happened the very night after a driveway i did, as it was from a vehicle that parked on the driveway and B and E'd the place. That driveway never showed any noticeable damage. People always used to ask and we always said wait a week. I have been told its 28 days to cure but i imagine its on a curve and thats the accepted point possibly as an engineering standard. I also worked on engineered formed slabs that had specific bent rebar for exact line of force applications. the slabs were kept both warm and in a mist spray as not to dry them out to fast for about a week as i remember. this allowed higher strength. after the forms were removed nuts were put onto the bent rebar which again improved strength in the slab. Oh course thats all overkill. the main thing i suggest and always do on my own stuff is spent a bunch of effort on a fantastic base. you don't want any water under a slab especially if there is any freezing exposure as it will lift the slab and form cracks/breaks. We call that "frost heave". More specific to you i have resurfaced floors before. All i did was use a slightly different mix so that the rock is a little smaller. Hopefully someone chimes in with an exact mix as i haven't done a slab over slab for a bunch of years. I know i wouldn't put fans on any job i worked on including the one you describe, though overall people wouldn't probably notice unless actual testing was done.
Best of luck sounds cool

 

[FlyingLow]

so how long sure I let it cure before moving things back on there, or parking a car in there again ?

You should call your local concrete place, they may have a quick dry formula. Quick dry concrete won't be the best choice for learning concrete finishing. I left my slab a few days before moving my stuff in but I had it in a sea can so had time. Generally forms are stripped after 24 hours but concrete is still "green" and chips easily. Concrete continues to harden the older it gets but officially it reaches it's full strength after 30 days. Putting much weight on it to early, like a car, could crack it easily. Look into bonding agents to bond it to the slab below, elmers white glue is supposed to be one of the best. You water it down and paint it on. Also get the fiberglass strand reinforcement added to the premix.

 

[Sheriff245]

24 hours before walking on it, at least a few days to a week before moving heavy stuff in.

FYI, concrete doesn't "dry" per se, it cures. Which means that the water reacts chemically with the cement to form solid material. Once it starts setting, you want it to stay in a moist environment for as long as possible to slow down the cure. That's what will give you the best durability.

 

[NZ0J]

I'm assuming by resurfacing, you mean you're putting a cap on the existing concrete. If it's a thin cap, under 2", I would wait every bit of a week, if not more.

As far as the fan goes, that is not a good idea. Depending on weather conditions, among other things, you could end up with shrinkage cracks.

 

[Falcon67]

Concrete cure is a chemical reaction, as noted above. It cures from the inside out. Fan won't do anything besides dry the surface water, which you really don't want to do. Just leave it alone and if possible, keep it wet.

 

[CheckeredFlag]

Good to know info

Thanks

 

[JakeKohl]

I had a material delivery truck back onto my brand new drive about 30 hours after it was poured and shake off a load of lumber on it.. I should have blocked it off but thought that the fact that it was blue (and obviously looked fresh...at a new construction site) might have been a clue. I also wasn't aware that the GC had scheduled the delivery.

No marks, no damage. whew.

 

[CheckeredFlag]

pretty lucky !

 

[JWC07]

Concrete generally is mixed to cure to its design strength in 28 days. I've seen a lot of 3 day cylinder breaks get to design strength.
You could easily walk on it in less than 24 hrs and drive on it in a couple days as stated above. You can gouge it and/screw it up pretty easy if you get on it too soon dragging and dropping stuff though.
I wouldn't want to try a high early strength if I wasn't quick and good at finishing.
If it's just a matter of not wanting to leave stuff out. You can probably get on it late at night if you do it early. Just lay down some plywood that night to set your stuff on then move it to its final location after it sets up a little more.


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[bobscogin]

What I'm trying to accomplish is- get the project done first thing in the morning, and be able to move things back in at the very end of the day ...
TIA

Tell the concrete producer what you're trying to accomplish and he will likely recommend a "high early strength" mix. These mixes are normally designed with higher sack contents, plasticizers, and other admixtures to accelerate hydration. Be prepared to pay a premium, however.

Bob

 

[alky]

Concrete generally is mixed to cure to its design strength in 28 days. I've seen a lot of 3 day cylinder breaks get to design strength.
You could easily walk on it in less than 24 hrs and drive on it in a couple days as stated above. You can gouge it and/screw it up pretty easy if you get on it too soon dragging and dropping stuff though.
I wouldn't want to try a high early strength if I wasn't quick and good at finishing.
If it's just a matter of not wanting to leave stuff out. You can probably get on it late at night if you do it early. Just lay down some plywood that night to set your stuff on then move it to its final location after it sets up a little more.

+1
also if you do drive a vehicle on try not turning the wheels, that marks it on fresh concrete. The plywood is an excellent idea.
I am curious if a 3 day cylinder break is a standard type of test for concrete.
I was just a form builder and placer/finisher w no actual knowledge.
All i can offer is things i was shown, told and how the crews i worked with did it. I sold the power trowel and kept my hand tools, only do a few jobs for freinds/ family a year now.