Wet curing slab (Ponding)

Hey guys,

My slab gets poured on Tuesday morning and I just want to ask what is considered the best method for curing?

My plan is to turn up in the afternoon and build a sand bank up along the outside edge or on the top perimeter of the slab (which method is preferred?) and then flood it with water and I presume its best to leave the hose running on a low pressure to allow for any water that escapes the dam wall?

Would it be better to build up the sand bank on the slab to divide it into 4-5 rectangle sections??

I should be able to visit site around 3-4 times a day for a week to check on it and fix any sand banks that have failed,
Am I on the right track here, what has everyone else done??

Thanks in advance!

I just came mornings and nights for a few days and watered it myself with a hose. I didn't build any dams or anything and it came out fine. Having said that it was winter and not very warm out.


Sent from an iPhone please excuse the ridiculous spell correcting software. My forum thread is at viewtopic.php?t=74944

That sounds like a plan for the same edge all the way around slab edge if possible as small dams will have lines of drier areas in my opinion. It is great you are curing the concrete. I covered my slab with plastic for a few days but I had a pour 5/8 so not hot weather. Curing concrete is the best practice you can do for your slab. Curing is not done by many of those building these days to the detriment of the concrete. Well done in my opinion.

Thanks Goody! I can't believe more people don't cure their slab, its such a critical step.
So would it be best to leave the hose running while I'm away from the site?

I honestly don't know how to continue the ponding method over the curing period you have selected as I only did the cover with plastic method on mine in very mild weather and had my slab left for 7 days before framing commenced.

Ponding is the best method of slab curing and I have done it many times. It will also give you advance warning if your slab levels are out, peaks and hollows.

Good point building expert
What would the acceptable tolerance be for slab levels?

another way is to cover it with hessian. Soak it all. Then just lay a soaker hose on it to keep the hessain wet.

To cover a large floor slab with hessian maybe a bridge too far ( and too expensive ) for a lot of people. The ponding method is probably the cheapest and easiest to do.

Stewie

I've just headed over to start the ponding and there was a pest control guy spraying a chemical curing compound onto the slab.

Should I still follow through with my plan and if so is it best to leave the chemical spray for a few hours to dry out???
Will flooding it have an adverse reaction in conjunction with the spray??

If you have chemically applied curing agent i would not be ponding. Chemical curing works well too. It can sometimes be an issue with aftertrades and slab adheasion for tiles and the like. It may require grinding off for aftertrades. Look into product applied. Name product and research. That is my suggestion.

Oh and I was so excited to set up the ponding! LOL

Ok well maybe I'll just leave it to do its thing and hope for the best. I should of asked the guy what product he was using but I didnt think to at the time so its too late now.
Thanks Goody!

Pest control spraying curing? That sounds sus to me, I would be asking questions.

That was my first thought too but I have since done some research and found there are quite a few pest control businesses offering this service...who would of thought!

I am not surprised that they do it. They have the spray equipment. The part that surprises me is that your builders are paying for concrete curing and that they are actually curing the concrete. Good on your builders. Not many builders do curing of their slabs. It cost me extra.

Heres one i found on the net (not affiliated in anyway )
http://www.bonneypestcontrol.com.au/concrete-curing/

It boggles my mind a little the Pest Controllers are doing this. they have to be licensed to handle some of the chemicals they deal with, but as far as concrete curing goes, I just wonder what the regulation, if any, is on this? Qualifications/skill in application, and what about the suitability/quality o the compound they use? who is liable if it goes wrong?

Slabs to me are still the most mysterious part of a build and something of a black box, and therefor the most dangerous part of the build.

Forming up and pouring a slab is pretty straightforward qebtel - as long as you get all the fundamentals right as you probably already know...
- prepping the site
- using the correct steel with laps, spacings right etc
- getting the formwork square, level, braced etc
- ordering the right strength in the right quantities
- placing, vibrating and finishing it off properly
- curing it properly
The chemical reaction of wet to dry concrete granted has a bit of science behind it but the actual pouring of a slab to me is pretty simple. However it continues to amaze me how many times I see on this forum and others where professional concretors have totally cocked it up and come up with some half ar$ed excuse why it happened.

Stewie

I had a subbie there doing the drains today and he was thoughtful enough to leave a mountain of sand on top of the slab
Will this have a negative effect on the slab curing? Will it leach moisture out of the concrete or anything?

that is the "mystery" i was referring to.

This topic's been interesting, and timely. A 9x6m slab for an extension, and immediately Off Topic, I specified the Cupolex system. Like Waffle Pods, they are dome type forms.
Their major benefits are that they stack, like plastic chairs, so instead a truckload of pods, a HiAce will do!. As they are engineered, there's an absolute minimum of waste. Installation can be done by any DIY'er, even me. Proper placement requires proper marking out.
The mesh sits directly onto the domes, no bar chairs. In my case, the slab top was only 60mm. Cost comparison for this job were close, but your mileage may vary.

Back to the curing issue, still needed here. Slab was poured last Thursday, which was fairly hot, mid 30's. Concreters left early afternoon with instructions to spray it in the evening, nothing more.
I did so, but noticed that even a good soaking dried out in less than 30 minutes.
Having already spotted this, and prior, topics, I'd grabbed a linear type sprinkler and timer from a big g shed.
Once installed, I set it on to a 3 minute spray every hour. (the minimum frequency of the timer)
Even this still saw drying out within the hour.
Packed away were a number of felt strips of drop sheet, so a bit of plastic backing.. I used these to cover half the slab, along with other felt type moving blankets. This appears to have worked well,, as i've lifted to see it's still damp below. I deliberately left an area au naturelle for comparison. The slab will never be seen, so cosmetic cracks don't phase me, though I do want the slab to cure to maximum strength.
Just revised the timing, so that after dark I change the interval to every 4 hours.

Now, following Stewie D's instructions..