Cold Weather Gunite Questions

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BluePool78

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Dec 31, 2017
12
Rochester, MI
All...thank you for reading my post.


We are currently in the middle of our pool build...yes, in December...in Michigan...


Our PB moved forward with applying the gunite and my concern is that it was done at very cold temperatures and that the following “curing days” are very cold as well. Everything I have read says the temperatures should be over 40F and to use some method of cold weather protection if there is a chance of below 40F. Our PB used a dry-mix gunite that was mixed as they used it on site, the bags were labeled Type IA Portland. At what point should we be concerned and what should we be looking for in terms of defects (if any) and are there any questions we should be asking?


The temperatures during the application of the dry-mix gunite was about 25-30F with the days following in the -5 to 20F range. There was one day when they were applying the gunite that it was about 10-15F.


The pool and attached spa are estimated to be about 45-50K gallons and the depth ranges from 3.5 to 9 feet deep.


Thank you in advance for your thoughts.

 
Only petrographic analysis could tell you if there’s a problem. It would require someone to remove several core samples and then send them to an independent lab like this one -

American Petrographic Services, Inc.

Doubt your PB would agree to it or be bound by the results though. I agree with JamesW that it’s very disturbing the PB has the job done under those conditions. The PB is responsible for the integrity of the shell and if anything goes wrong, one could easily make the case that the finite was not properly done.

Not sure what you can expect to achieve? Do you want the shell ripped out and redone? That’s going to be a non-starter in any PBs book....
 
Happy New Year everyone.

Thanks for unfortunately confirming my concerns. My goal here is to try to understand WTH the PB was thinking and also to prepare for our meeting with him in the next week. I don’t necessarily think a rip out is likely and assume he would have lots of reasons why that is not needed.

A couple of additional questions as we are preparing to meet with the PB in the next week or so.

Is there anything we should notice at this point to know if we may have future problems? I can easily enter the shell and look, feel, take pictures, etc for issues...if I knew what to look for...

Can applying the gunite at such cold temperatures be offset by having very thick gunite in the bottom and the walls of the pool structure/shell...or possibly a higher amount of rebar installed?

About how many days of curing is required or considered “safe” to be exposed to extremely cold temperatures such as down to 0 to 10F?

Is there anything specific that I should ask the PB about this?

The PB is very well known and considered the premium PB in our region and has been in business for decades... Katie’s several of his installations and they are amazing...so it baffles me why this appears to be a potential issue...but here we are. Maybe we are overreacting but I appreciate all of the knowledge from this group.

Thank you again for all of the input.
 
Gunite creates its own heat as it cures. This heat is enough to keep it above freezing. The question is was the curing process far enough along before the water might have froze. I think as stated above the only way to tell is a core sample sent for analysis. I suppose you could suggest that and say you will pay for it if it comes back ok but if not, the PB will remove the gunite and start over. Pointing to the lifetime warranty (or whatever they are offering on it) is not really enough. If you ever have to cash in on that warranty you will have an enormous mess. And not sure the warranty will cover anything accept the shell being redone. Definitely resolve this before you move on!

If you go put your hand on the shell, is it warm? Do you have a heat gun (laser type) that you can see if the temperature is warm?
 
They shot the pool and then put up some visqueen to shelter from the snowstorm that dropped 7”...no heater.

- - - Updated - - -

Nothing is warm, but it is cold as heck here in Michigan right now.

Any idea on about how much time at 25-35F is enough time (if any) before a significant freeze such as 10F. I wonder if the outside exposed surfaces cure first and possibly protects the core so it has more time to cure and does not directly see the frigid cold?

Our PB seems to really know his stuff, builds pools all winter here...and is the premier builder in our area...but I’m just stuck on this. Meeting with him later this week.

Thank you again for any addition thoughts and input.
 
Found this article...

dee Concrete | Cold Weather Concrete Tips

Do not begin final finishing operations while bleed water is present.
Ensure proper finishing with no extra water or excess bleed water worked into the surface or over-finished
Don't over work cooled slabs that exhibit delayed setting characteristics.
Ensure that your cold weather concrete has cured and do not allow hardened concrete to dry out.
Keep ice from forming - Once ice has formed, hydration stops and strength development is seriously impaired. Fresh concrete frozen during the first 24 hours can lose 50% of its potential 28 day strength!
Use insulation blankets or heated enclosures to maintain concrete temperatures above 50° degrees Fahrenheit for three to seven days.
Use a good quality curing compound if you are unable to maintain concrete temperatures above 50° degrees Fahrenheit for three to seven days.
Maintain the concrete temperature above 40° degrees Fahrenheit for at least four more days after the use of the insulation blankets or heated enclosures.
Do not seal freshly placed concrete.
Remove the heat protection in a manner that ensures the temperature of the concrete will not drop faster than more than 40° Farenheit in 24 hours.
Click to expand...
 
To the OP,

At this point, I don't think there's much left to say in this post. No one here is a concrete expert and there are simply two options open to you -

1. Accept the assurances of the pool builder that your shell will be fine and rely on the warranty that is offered to you for any future issues; OR

2. Halt the work and seek an independent 3rd party expert (consider the links that JamesW and I posted) to analyze the concrete that has been put in place.

Beyond that, there's not much else you can do.

Good luck to you and let us know how your conversation goes with the PB.
 

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I am shotcrete application and defect consulting SME. When I get a few more grey hairs, it will be all I do.

Mixes may be chemically prepared for extreme hot or cold weather shoots. The alterations and post shoot labor are expensive and demand significant $$ change orders. The alterations are misunderstood by majority of concrete suppliers and applicators.
 
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