Downpour during gunite application

[dphanes]

This past week the pool company put in our gunite shell. In the middle of spraying the gunite there was a downpour that was about 0.5 inches of rain. I am now concerned that the strength of the gunite is compromised. They used #4 rebar and the floor is 8 inches thick. The Gunite company website says they use a mixture that is 5,000 PSI, but I am concerned about the additional water weakening the gunite.

If all the rain was absorbed into the floor then my math (38 by 18 pool with 0.5 inches of rain is 210 gallons.; 38 by 18 by 8 inch floor is 17 yards of gunite) is that is an additional 12 gallons of water per yard of gunite. The conversions I have seen online suggest that would weaken the gunite by 150 PSI per gallon or 1,800 PSI which means the final strength is 3,200 PSI.

Am I missing something and should I be concerned?

Thanks

 

[spd500]

Did it rain the whole time the gunite was being applied, or after they were finished? If it was during the application and the water is truly mixed into the concrete it will weaken it, but if the concrete was already there and then rained on it will not have much of an effect.

I have done alot of concrete in industrial settings and have always done break out tests on concrete for insurance purposes, and mentioned to my wife that I was thinking I would get breakout tests done when they did our gunite and she thought I was insane, but this is one situation where it would be beneficial to have them.

I am not sure what options you would have with a pool builder, but in industrial and commercial jobs if we ever had concrete that failed the breakout tests the company would take out a bond on the job to insure that if the concrete ever failed the expense would be covered. It might be worth talking to the builder about what options you have if you really feel the concrete was compromised.

 

[dphanes]

It rained for about 30 mins while they were spraying the gunite (although for the period it was actually raining they stopped spraying). A layer a couple inches thick had been laid earlier in the day but when raining you could see it mixing with the top layer and was making a wetter mixture. After the rainstormended they completed spraying the rest of the gunite

Is a breakout test essentially taking out a round cylinder of the concrete and doing a stress test on it to see at what PSI it breaks?

Thanks for your help.

 

[spd500]

It is probably going to be fine, but maybe someone with more pool specific experience will chime in. In most conditions I have worked in where there was a chance of rain we tried to be prepared to cover the pour with sheets of plastic , but I have seen many jobs where there was a short rain during the pour that didn't create any failure.

The breakout test is where you sample the concrete from the truck at the time of it being poured, after the sample is taken they are not supposed to add water to the truck or the pump because it changes the chemistry of the concrete. We always took samples for 7 day, 14 day, and 28 day tests and there is a chart that you would follow for each of the tests that said what each particular mix should test at for each time frame. The early tests in our situation would let us know as early in the project as possible if there were any obvious issues, but the last test was the real number that you were looking for the rating of the concrete to meet.

 

[bbqjosh]

This past week the pool company put in our gunite shell. In the middle of spraying the gunite there was a downpour that was about 0.5 inches of rain. I am now concerned that the strength of the gunite is compromised. They used #4 rebar and the floor is 8 inches thick. The Gunite company website says they use a mixture that is 5,000 PSI, but I am concerned about the additional water weakening the gunite.

If all the rain was absorbed into the floor then my math (38 by 18 pool with 0.5 inches of rain is 210 gallons.; 38 by 18 by 8 inch floor is 17 yards of gunite) is that is an additional 12 gallons of water per yard of gunite. The conversions I have seen online suggest that would weaken the gunite by 150 PSI per gallon or 1,800 PSI which means the final strength is 3,200 PSI.

Am I missing something and should I be concerned?

Thanks

I would check your engineering plans, mine called out 4000 psi concrete. But I wouldn't be surprised if it was 3000 psi. You can search online and see the arguments between the psi between engineers and concrete companies. I think they go as low as 2500 psi in some cases. When I inquired from my gunite company, they said they do 100 percent of residential pools in the 3000 psi range and then 4000 psi for commercial pools. I would check the guarantee from the company for warranty. That's my 2 cents.

 

[dphanes]

I would check your engineering plans, mine called out 4000 psi concrete. But I wouldn't be surprised if it was 3000 psi. You can search online and see the arguments between the psi between engineers and concrete companies. I think they go as low as 2500 psi in some cases. When I inquired from my gunite company, they said they do 100 percent of residential pools in the 3000 psi range and then 4000 psi for commercial pools. I would check the guarantee from the company for warranty. That's my 2 cents.

Thanks for the response...