curing shotcrete W. PICTURES. Now found CRACK

Dec 19, 2011
36
Orange County, CA
The pool was poured Thursday. Initially, the plan was that the builders will do the first watering. They finished later then expected, said the concrete was too wet to water, and I should water it Friday. I watered Friday morning and afternoon (it was extremely dry and windy). While watering Saturday, I noticed a few spots that are lighter/look "dry" compared to the rest of the pool (concentrated on the edges of the spa - seats and step, but a few spots in other places as well). Is this really bad? Also, what is the proper way to water?
 
Re: curing shotcrete - is this a problem?

The description and placement of the contrasting concrete makes me suspect that it is rebound. Rebound is concrete that has fallen off of applied surfaces or been trimmed. Some builders will use rebound to build out areas that need a little more concrete. It is not a good practice.

Ideally, the concrete should be kept continuously moist by a fine spray, or mist, for the first 7 days. Intermittent wetting and drying can have an adverse effect on the concrete.

http://www.pooleng.com/Use-of-Rebound-i ... av-62.aspx

http://www.shotcrete.org/pdf_files/Spri ... DryMix.pdf

did-your-pb-s-shotcrete-sub-reuse-the-shotcrete-rebound-t3643.html

http://www.concrete.net.au/publications ... ring06.pdf
 
Re: curing shotcrete - is this a problem?

JamesW said:
The description and placement of the contrasting concrete makes me suspect that it is rebound. Rebound is concrete that has fallen off of applied surfaces or been trimmed. Some builders will use rebound to build out areas that need a little more concrete. It is not a good practice.

Ideally, the concrete should be kept continuously moist by a fine spray, or mist, for the first 7 days. Intermittent wetting and drying can have an adverse effect on the concrete.

http://www.pooleng.com/Use-of-Rebound-i ... av-62.aspx

http://www.shotcrete.org/pdf_files/Spri ... DryMix.pdf

did-your-pb-s-shotcrete-sub-reuse-the-shotcrete-rebound-t3643.html

http://www.concrete.net.au/publications ... ring06.pdf

Yes, I think they have used some rebound. It looked like this was a typical practice for this crew.

They just told me to water it with the hose twice a day. I am doing more than that today, but I do not see how continuous misting for a week will be feasible ... :(

The PB does have a lifetime warranty on the shell, and they have been around for a long time ... you'd think they will know what they are doing.
 
Re: curing shotcrete - is this a problem?

DBfan187 said:
put a sprinkler in the pool and let it run?

Yeah, I tried that yesterday - it was more of a mess than help, but I can try tinkering with the thing again today. The pool is long and narrow, so ideally there would be 2 sprinklers. Looks like it might rain - that would be helpful...

Now, should I bring up the rebound issue with the builder? What could they realistically do? Most of it is in the spa and steps, but it looks like there is also some in the floor.
 
Re: curing shotcrete - is this a problem?

It probably wouldn't hurt to ask the builder why the sections look different to see what they say. Without being able to inspect the concrete in person, it's hard to say for sure if it might be a problem.

Check the rebound areas to see if they feel solid. If they feel weak or crumbly, then the areas definitely need to be fixed.

If they feel solid, and the builder checks them and says that they are fine, at least you are on record about the issue. It probably wouldn't hurt to take pictures of the areas and make detailed drawings with measurements in case there are cracks in those areas.

Regarding watering, most people water at least three times a day and that's usually fine. The ideal situation is to rig up some sort of misting system to keep the concrete moist at all times, but that's usually not practical. You might be able to rig up a soaker hose on a timer or some other such contraption.
 
Re: curing shotcrete - is this a problem?

Thank you, this is very helpful. I defintiely plan on taking pictures and getting this on . Also, there is one spot that looks like it is crumbling, but it is not where the color is different, but one of the other edges.

I got finally got the sprinkler set up so it covers most of the pool, and I just need to water some in the corners. Is it eccential to get every inch of the pool moist?
 
Re: curing shotcrete - is this a problem?

The edges will always dry out faster than the other areas, so just the drying out doesn't necessarily indicate that rebound was used, or that there is any problem with that area.
 

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Re: curing shotcrete - is this a problem? PICTURES ADDED

That looks OK. I don't think that it from rebound. I'm not sure what caused the lighter areas, but it seems fine unless the areas feel weak.
 
Re: curing shotcrete - is this a problem?

JamesW said:
The description and placement of the contrasting concrete makes me suspect that it is rebound. Rebound is concrete that has fallen off of applied surfaces or been trimmed. Some builders will use rebound to build out areas that need a little more concrete. It is not a good practice.

Ideally, the concrete should be kept continuously moist by a fine spray, or mist, for the first 7 days. Intermittent wetting and drying can have an adverse effect on the concrete.

http://www.pooleng.com/Use-of-Rebound-i ... av-62.aspx

http://www.shotcrete.org/pdf_files/Spri ... DryMix.pdf

did-your-pb-s-shotcrete-sub-reuse-the-shotcrete-rebound-t3643.html

http://www.concrete.net.au/publications ... ring06.pdf

Sorry did not read the whole thread - I agree never use rebound in the structure


http://www.youtube.com/watch?v=HbwUkpyogyM
 
Re: curing shotcrete - is this a problem? PICTURES ADDED

Thanks guys. I was seriously freaking out. Here is the picture of the entire pool - let me know what you think. It is 40X14, integrated spa, will have automatic cover.
 

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Re: curing shotcrete - is this a problem? PICTURES ADDED

aniceone said:
Thanks guys. I was seriously freaking out. Here is the picture of the entire pool - let me know what you think. It is 40X14, integrated spa, will have automatic cover.
The Shotcrete Shell looks good - behind the skimmer looks good also - if your worried about rebound in the cove and floor ,sound it with a hammer -if it sound's hollow it is most likely REBOUND
Chris
www.shotcrete.us
 
Re: curing shotcrete - is this a problem? PICTURES ADDED

Thanks! I may try the hammer thing (with a little light one!).
Construction supervisor came this morning and said to stop watering, it's all good and they will be preparing for the masonry. Today is Wed, and the pouring was last Thur. Is this weird? And of course I JUST got the sprinkler tweaked so it can cover the entire pool!!
 
Re: curing shotcrete - is this a problem? PICTURES ADDED

aniceone said:
Thanks! I may try the hammer thing (with a little light one!).
Construction supervisor came this morning and said to stop watering, it's all good and they will be preparing for the masonry. Today is Wed, and the pouring was last Thur. Is this weird? And of course I JUST got the sprinkler tweaked so it can cover the entire pool!!
Usually the water cure is seven days - Concrete cures for 100 yrs - more water will not hurt it
as to the Hammer use any size you want -you will not hurt it - sound the wall first then sound the cove and floor -they should sound solid
take some pictures of the cove and floor
CZ
 
Using your sprinkler as a scale, it certainly looks like you might have a crack somewhere in the neighborhood of 1.5-2m long. The pattern of surface evaporation in addition to the visible portion of the crack at least gives that impression. Repairing it at this point shouldn't be too difficult I wouldn't think. Mabey they can drill a hole and pump epoxy or a very thin cement slury into the crack? Did the shell dry evenly? Is the sun shining more on one side than another?
 
Yes, that is what it looks like to me, about 1.5-2m, and maybe 2mm wide. I believe the side where the crack is gets a little more sun than the other side, but it really depends on the time of the day. It looks like list of the pool dried evenly, but not perfectly (although water on the bottom of pool and spa makes it hard to judge.
The company said they will come over and check.... i am just concerned that the curve between the wall and the bottom is really not a nice place for a crack... and if it is cracking already - scary....
 
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