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Sidewalk Pour, Frozen Ground


mossman's Avatar
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01-26-18, 07:51 AM   #1  
Sidewalk Pour, Frozen Ground

I'm having a new sidewalk poured tomorrow and need some advice on how to ensure everything goes smoothly and the pour is not compromised by the cold weather. It has been in the teens and below for the past several weeks, so the ground is frozen solid. Temps will be in the lower 30s for the next two days, then will drop to the teens and 20s for the following several nights. At a minimum I asked that they thaw the ground and use heated curing blankets to cover the fresh concrete for at least 3 days. Any other precautions they should take?

 
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01-26-18, 08:10 AM   #2  
Do a search for ACI 306-Standard Specification for Cold Weather Concreting and follow that. Do not allow concrete to be placed of frozen ground. Depending on how far down the frost goes, it may take a long time to thaw. Dig down in a couple places to ensure it's thawed all the way down.

 
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01-26-18, 08:11 AM   #3  
The heating blankets should have been on the ground the entire week.


 
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01-26-18, 08:31 AM   #4  
I was afraid of that. Having them tear out the old sidewalk and pour a new one tomorrow doesn't sound wise at all. I will tell them to hold off. I was hoping they could lay heating blankets for 24 hours and that would suffice, but it doesn't sound that way. Glad I asked!

 
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01-26-18, 09:47 AM   #5  
You have been having problems since day one with this whole project. I would not press my luck trying to get the pour done on Saturday.

 
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01-26-18, 10:15 AM   #6  
You have been having problems since day one with this whole project. I would not press my luck trying to get the pour done on Saturday.
I agree. They are the ones pushing it. I told them not to do it. The builder just emailed me and said they removed all of the original sidewalk and the ground isn't frozen underneath. 2+ weeks of 20s, teens, and single digits and the clay soil underneath isn't frozen???

 
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01-26-18, 04:44 PM   #7  
Pound a 4 inch nail where the pour will be and insert a thermometer probe into the hole and see what it reads.


GregH.........HVAC/R Tech

 
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01-29-18, 07:43 AM   #8  
They went ahead and poured the walkway on Saturday. They drove a stake in the ground to show me the soil wasn't frozen, even though surface temperature of the stone base was right at 32 degrees. I imagine the only reason the soil wasn't frozen is because it was protected by the old walkway and several inches of mulch around the perimeter. I hit the area with a torch for a few minutes until the truck arrived and was able to get the stone up to about 45 degrees. The ambient temperature made it up to over 60 on Saturday and it was sunny, and the nighttime temperature was 47. I laid an insulating blanket on top that evening, which I plan on leaving in place at least until Friday. It's going to be a high of 46 today and 30 tonight, then high of 36 tomorrow and low of 19. I think it should have reached 500 psi by now, so hopefully I'm in the clear.

Oh, they started finishing with their steel floats right after they screeded the concrete, then waited about 30 minutes, finished some more, waited 20 minutes, then applied a broom finish and immediately took off the forms . Basically did the complete opposite of everything I have heard/read/seen about proper concrete placement. I'll be sure the 2-year warranty explicitly states that defects (cracking, spalling, crumbling) are covered.

 
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02-10-18, 07:48 AM   #9  
Well, it's been two weeks, raining off and on, freezing overnight temps and it isn't looking good...

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03-11-18, 04:20 AM   #10  
easy to see why - too much wtr,,, see all the micro-crking in the paste ? ? ? there's a reason aci publishes cold-weather concreting specs,,, your guys were either ignorant, idiots, or didn't give a ****,,, then again, they could've been a combo

 
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03-12-18, 07:45 AM   #11  
your guys were either ignorant, idiots, or didn't give a ****,,, then again, they could've been a combo
I would say all the above. How long until this will start to crumble? I still owe the builder a large chunk of money, so I have leverage. This is the second time they've had to do it. Ridiculous.

 
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03-13-18, 04:58 AM   #12  
just happened to think - was this conc mixed up on site OR was it the same part of another conc load delivered by redi-mix truck ?

 
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03-13-18, 06:05 AM   #13  
It was delivered. I watched them, and they started finishing immediately after they screeded.

 
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04-13-18, 12:14 PM   #14  
The entire sidewalk shows this fracturing just below the surface. It is more noticeable when it is wet. Is this something I need to be concerned with in the near term? How long before the surface starts crumbling? After a few more freeze/thaw cycles?

 
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