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Pouring a slab in 90+ heat

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philshevlin

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I'm in the planning stages but expect to pour my mono slab in the next month. Its been 90+ the whole summer and I expect it won't change much.

I've been researching, but was hoping for some help too.

What should I look/listen for when talking to contractors and concrete companies? I will be subbing out the pour.

Thanks!
 
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Milton Shaw

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The thing is keeping it wet and wetting down the gravel before you pour. In that kind of heat you will have less than an hour total to finish the concrete before it's too hard to smooth any more. The contractor has to have enough people to handle the concrete before it sets up.. If you can postpone the pour until fall and the concrete will be much better in the long run. IF it takes two trucks make sure its there so that one half the slab doesn't set up before the rest gets there.
 
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Jackfre

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I did mine in big heat last year, As noted, plenty of hands, once mine was done I covered it with plastic and put a sprinkler on it. Occasionally I'd pull the plastic back and flood the slab. The plastic marked the slab but I painted the slab with rust bullet and it came out fine. Good luck
 
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Jackfre

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Oh, and I cut the expansion joints next morning and covered it for about a week.
 
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NUTTSGT

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If you were doing a traditional footer/wall/floor, you do the floor after the roof is on giving the concrete some shade from the heat. Since you are doing a monolithic slab, until it's done, all progress will stop. Milton has given you some good information.
 
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brownbagg

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we do it every day, plenty of help, mix with chilled water, get a reducer or a super p added. pour early, we do most at 3 am to 5 am. and dont play around, you got about 45 minutes per truck. dont have truck waiting on you
 
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Sharpest

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I am in the middle of pouring 23 post tension foundations for an apartment complex in south Texas. They range in size from 5000-8000 sq ft each and are 200-350 yards of material each. Start EARLY in the morning, like 3am-ish when its the "coldest" (lol...) time of the day. This gives you maximum time to work the material and also helps with the laborers' endurance. Try and figure out a way to have the trucks either all on site at once or staggered so there is zero wait between them. Cold joints will derail the whole operation. Our deal with the concrete supplier is "if you F' us over once and make me wait on trucks, we use someone else next time" There are lots of options around here so we aren't bluffing.
 
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philshevlin

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East Tennessee
brownbagg said:
we do it every day, plenty of help, mix with chilled water, get a reducer or a super p added. pour early, we do most at 3 am to 5 am. and dont play around, you got about 45 minutes per truck. dont have truck waiting on you
Click to expand...

What is "plenty of help?" Its a 30x60 mono slab.

On one quote I got the guy said 3 guys total.
 
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MoonRise

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philshevlin said:
What is "plenty of help?" Its a 30x60 mono slab.

On one quote I got the guy said 3 guys total.
Click to expand...

3 guys? For a 30x60 slab in 90+F weather? Place the concrete, screed it, jitterbug it, bull float it, trowel it, and form the edges and the expansion joints? In less than an hour?

NFW. :eyecrazy:

More like 5-10, and those guys will be working hard for that 1 hour before the concrete sets up.

Because concrete waits for no one.

http://www.concretenetwork.com/hot-weather-concreting/

Proper additives, have the 'mix' cool (chilled aggregate from the yard, easy on the mixing because the friction can raise the mix temp 5+F, chilled water and/or ice, try to keep the mix temp below 80F), maybe use an evap retarder, wet down the subgrade well before the truck(s) show up, make sure all the prep and form work and subgrade work is completely done and checked and double checked at least the day before (because there will be no time to do anything except the pour when the trucks arrive).

Do-able? Yes.

3 guys? NFW. IMHO.
 
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philshevlin

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I hate to do it, but I may postpone until mid Sept.

This may not be too hard because in Tennessee getting contractors to return calls, let alone show up, takes at least a month -- if at all!
 
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Sharpest

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I agree with MoonRise, 3 guys is not enough for any time of year, much less summer. For reference, I have 20-25 men working the slabs I mentioned above. Every one of them has a specific job, knows how to do it, and does it for 5-6 hours for the duration of the pour.
 
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Falcon67

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My pour started at 6:30, it was over 105F by afternoon. I watered the slab with a sprinkler from Saturday morning until Sunday afternoon. Sunday after the water evaped slab was 135F. No issues. That was August 2011 and it was 100+ every day from pour until I think winter. Not sure about TN but here September is usually as hot as August. They pour here hot or cold.

11 guys poured the house slab next door, about 3200 sq/ft, 92 yards. Started at 6 AM, forms off by 2. Not a hose or sprinkler one on that slab, nor on any other house foundations I've ever seen poured here.
 
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MOwens

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My floor (3000 square feet) was poured last week in two days during 90 to 100 degree days with 3 guys and the forman. They cut and poured the piers and frost wall 4 foot deep on friday. They came back monday and set forms all day and packed and graded the ground. On tuesday they poured half my 6" thick floor with rebar and power troweled it. Wednesday they poured the other half. Thursday we poured the aprons around most of the building. We are waiting on the plumber to finish up his install and then we can finish the apron. We didn't wet the concrete and the finish is amazing and flat. The only cracks I have are where they were cut into the concrete. I went with my contractor because he is the best concrete guy in the business which is one of the most important parts of your building. Here is a crummy security camera picture.
 

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philshevlin

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As usual for internet forums 50% say go for it... 50% say don't do it.

I'll flip a coin come Sept. But I definitely received and appreciate the learnin' I asked for.... and got.

Thanks
 
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wssix99

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Chicago, IL
philshevlin said:
As usual for internet forums 50% say go for it... 50% say don't do it.

I'll flip a coin come Sept. But I definitely received and appreciate the learnin' I asked for.... and got.

Thanks
Click to expand...

You can pour concrete at any time. You just have to make different allowances for the weather and conditions.

... Just don't wait too long. If the temperatures get below freezing, we'll need a new thread!
 
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mitusa

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brownbagg said:
noooooooo, you cant do this, concrete will set in the truck, never have all the mud at one time.
Click to expand...

^^^^this. Try to space it out so that one truck comes a few minutes after the last truck empties. That will give you some time to get ready for the next load.
 
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jeepntxj

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Jul 19, 2009
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brownbagg said:
noooooooo, you cant do this, concrete will set in the truck, never have all the mud at one time.
Click to expand...
X2, unless you can pour all the trucks at once!

Simply find a company with a chiller or is set up to throw ice. Shouldn't be hard to find.

We have 2 big contracts we're supplying the concrete for right now, and they are both "temperature controlled". One averages 250 yds per day, with (25) 40lb bags of ice per load and the other is 1200 yds per day using chilled water. We have a Pearson 100 ton chiller giving us 41° water all day, and each load calls for 2200 lbs of water.

This is in Southeast Texas where we are hitting 100-102° daily.
 
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