How long would you let your ShotCrete set up/dry before finish?

[Frank Rizzo]

I'd like everyones opinions here...best practices, etc.


Obligatory pic:

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[jblizzle]

I am not sure what the standard is. But, it is usually a good idea to spray the concrete down a few times a day to slow down the curing.

 

[Titan7]

28 days

 

[MarkTX]

Not an expert, new pool myself, but seems like the PB waited 3-4 weeks, without any reason other than to wait.

 

[Frank Rizzo]

What I was thinking...thanks. Just like concrete....

 

[BigEinAZ]

28 days

More like 7 days . . .
http://www.pooleng.com/_coremodules/common/secure/fv-145.aspx
You could do waterline tile even earlier if you wanted to.

 

[BigEinAZ]

I am not sure what the standard is. But, it is usually a good idea to spray the concrete down a few times a day to slow down the curing.

Keeping the concrete damp doesn't slow the curing, it enhances it. Concrete cures through a chemical process called hydration. Free water is necessary to sustain hydration and to lessen the occurance of shrinkage cracking. The first three to seven days are the most critical since that is when approximately 85% of the ultimate strength is obtained.

 

[jblizzle]

Thanks BigE, I was not clear with my response. Yes it enhances the curing to lower likelihood of cracks ... in my mind, by slowing the surface curing.

 

[Frank Rizzo]

More like 7 days . . .
http://www.pooleng.com/_coremodules/common/secure/fv-145.aspx
You could do waterline tile even earlier if you wanted to.

Thanks. But that wordy article - that does not really answer the question - but it does say that the only time you would wait a mere 7 days is in the case of exposed or out of grade shotcrete where you needed to back fill. Later on in the article it talks about 100% strength in 28 days and not to fill the pool with water before the 28 day period.

 

[BigEinAZ]

Thanks. But that wordy article - that does not really answer the question - but it does say that the only time you would wait a mere 7 days is in the case of exposed or out of grade shotcrete where you needed to back fill. Later on in the article it talks about 100% strength in 28 days and not to fill the pool with water before the 28 day period.

Frank, I don't read anywhere in the article that the pool should not be filled before twenty-eight days. That specific reference is to an unsupported shell wall. As long as the water level is below grade (fully supported) there should be no reason to wait that long. More important than compressive strength is flexural strength. As long as the shell is supported, there will be minimal flexural load on the shell. By fourteen days, most well proportioned concrete mixes will have reached at least 85% ultimate strength. If my pool builder was ready to fill fourteen days after shooting the shell, I wouldn't have any concerns.

 

[Frank Rizzo]

Frank, I don't read anywhere in the article that the pool should not be filled before twenty-eight days. That specific reference is to an unsupported shell wall. As long as the water level is below grade (fully supported) there should be no reason to wait that long. More important than compressive strength is flexural strength. As long as the shell is supported, there will be minimal flexural load on the shell. By fourteen days, most well proportioned concrete mixes will have reached at least 85% ultimate strength. If my pool builder was ready to fill fourteen days after shooting the shell, I wouldn't have any concerns.

Thanks for the explanation E. So it sounds like plaster in 14 days would not be a problem either.

One good thing about that article was that it pointed out if both sides of the shell are exposed (like my raised spa is) it's important to keep it damp because both sides are exposed to weather. Nice to know, easy to do.