Concrete curing in enclosed space

[BigBlue1]

I'm filling a lawn roller with concrete (building my own, actually). Before I cap off the roller tube after filling with concrete I'm wondering how long to leave the concrete cure? The fact that concrete can cure underground - such as in a sonotube or dumping concrete around a fence post - it makes me think it doesn't matter if I seal off the concrete inside quite soon, but the rational part of me says it needs some air circulation to allow evaporation. I'm looking for someone knowledgeable that can offer guidance here. Is it adequate to allow just enough time for any surface water to evaporate and then seal it or should I be waiting longer? I know that curing is a chemical process and not exactly evaporation, but I also know that evaporation does play a part.

Thanks,
Rob

 

[i7win7]

I bought a used 24" by 4' roller at auction cheap because the end plate leaked (rust holes). I set roller on end atop 3 or 4 cement blocks, used angle grinder to cut decent size fill hole. Filled with cement and allowed to cure a couple of days. This thing now weighs over 1 ton. I modified the hitch by attaching an automotive style trailer coupler and a bicycle kickstand. Place trailer ball om mower to back under it. I first used riding lawn mower to pull it. It takes 20+ HP to pull it, if tractor is too small (lightweight) it will push the rear end when you try to turn. After buying a BX2370 Kubota, I bought a 3pt trailer mover to connect to the beast, works great.

Things to consider - HP of your tractor, size of your roller and cement won't go down a 1" fill hole, It's trying to setup after mixing.

 

[bcp]

Concrete cures underwater, so I don't think evaporation matters very much.

Bruce

 

[BigBlue1]

Thanks. I'm already past all that. I have the roller made, out of an ancient steel water softener tank, and I have it filled with concrete. The hole on top was only about 1.5" but I made a funnel from a plastic jug and mixed the concrete at the upper end of the suggested water ratio (not over) and it filled OK with a little agitation from a garden scoop when it stopped flowing. I also have the rest of things well in hand. Just looking for guidance on how long before sealing the tank/roller up.

It's amazing how much more volume your 24" roller has than my 12" one. Mine is around 450#. I have made my roller frame to accommodate JD suitcase weights though so I can add a bunch more weight if needed.


Rob

 

[BigBlue1]

Concrete cures underwater, so I don't think evaporation matters very much.

Bruce

Good to know. That makes sense, since you can dump it in a post hole and then cover with dirt right away. But I just wasn't sure.

Rob

 

[/pine]

I would leave it vented until it no longer feels warm on the outside...

 

[BukitCase]

Me too; just because it's "cured" doesn't mean it won't still outgas. In fact, I wouldn't actually SEAL it at all, just cap it to keep bugs out... Steve

 

[Industrial Toys]

Concrete does not require air to cure. It's an exothermic (sp?) process. A chemical reaction. Cold will really slow it down though.

I bought one of my rollers with crushed stone in there. Plenty heavy enough. And no need to drain water every year.

 

[BigBlue1]

Me too; just because it's "cured" doesn't mean it won't still outgas. In fact, I wouldn't actually SEAL it at all, just cap it to keep bugs out... Steve

I'm not 'sealing' it, per se, but I am welding on the mount to support the flange bearing on the 'fill' side and that will cover the hole mostly. If airflow or circulation was important then it would be quite limited. But it isn't going to build pressure.

It's been in the 40's (F) here and it has been curing for about 48 hours now. It was 'solid' within 12 hours.

Rob

 

[i7win7]

Thanks. I'm already past all that. I have the roller made, out of an ancient steel water softener tank, and I have it filled with concrete. The hole on top was only about 1.5" but I made a funnel from a plastic jug and mixed the concrete at the upper end of the suggested water ratio (not over) and it filled OK with a little agitation from a garden scoop when it stopped flowing. I also have the rest of things well in hand. Just looking for guidance on how long before sealing the tank/roller up.

It's amazing how much more volume your 24" roller has than my 12" one. Mine is around 450#. I have made my roller frame to accommodate JD suitcase weights though so I can add a bunch more weight if needed.


Rob

450# roller, weight of lawn tractor unknown. I think you will have difficulty aligning 3 drawbar holes so it can be pinned on. Using a pair of clevises don't work very well either. Using the automotive style of trailer connection is cheap and much easier to connect even without a 3pt.