Start Watering New Gunite Right Away, or Wait?

[cwstnsko]

My pool builders advice was “it’s not possible to overwater the shell, our crews have pumps to deal with any excessive accumulation of water in the pool”. The gunnite crew had me start watering as they were leaving. Their rule of thumb was, if it turn light gray, water it until it’s dark gray, as often as it takes, for the 1st 7 days. In the end, you do what you can do.
The pool across the street was shot when nobody lived there. The builder set up an oscillating sprinkler on a timer, but all the other trades working on the house kept disconnecting the hose to use the spigots. I’d guess that his pool got watered no more than 5 times in the 1st week, mine got watered at least 50 times. In the end, his shell looked just like mine and his pool looks just like mine ?

 

[MeowMeow724]

My pool builders advice was “it’s not possible to overwater the shell, our crews have pumps to deal with any excessive accumulation of water in the pool”. The gunnite crew had me start watering as they were leaving. Their rule of thumb was, if it turn light gray, water it until it’s dark gray, as often as it takes, for the 1st 7 days. In the end, you do what you can do.
The pool across the street was shot when nobody lived there. The builder set up an oscillating sprinkler on a timer, but all the other trades working on the house kept disconnecting the hose to use the spigots. I’d guess that his pool got watered no more than 5 times in the 1st week, mine got watered at least 50 times. In the end, his shell looked just like mine and his pool looks just like mine ?

Great info!

I'd have to be in it all day for it to not turn light gray. Areas turn light gray before I'm even done the whole thing! probably should get a sprinkler on it for the time I'm not able to get on it during the day.

 

[MinerJason]

Great info!

I'd have to be in it all day for it to not turn light gray. Areas turn light gray before I'm even done the whole thing! probably should get a sprinkler on it for the time I'm not able to get on it during the day.

I wouldn't worry about it too much. The primary purpose of watering is to increase the strength of the final product, but even if you didn't water it at all it should be more than strong enough for the intended purpose (assuming proper mix and placement). You also live in a very humid climate, which will be beneficial to the curing. Just water it as often as is practical for the first couple of weeks.

Shotcrete / concrete is ready for water as soon as the initial set is complete, which is about 4-6 hrs after placement. Water is applied to aid in hydration/curing, a process which decays exponentially, so watering is most critical in the first hours/days after placement. Concrete will continue to cure/harden forever, but the strength used for design work is the strength after curing for 28 days. This is primarily because it's close to an inflection point in the strength curve with much lower strength gains afterwards (and 4 weeks is an easy timeline to use for construction purposes). As the chart below shows, it's really the first 7 days that are critical for keeping the concrete moist if you want to achieve full 28 day strength. But as I said above, even without watering it should be plenty strong enough.



Yes, there's a typo in the chart title. Not my chart though, just the first thing I came across in a google image search.

 

[MeowMeow724]

Soooooo.... What does it turning light gray so fast during the day, mean?
Either way it is what it is.. it would be impossible to keep it moist the whole time.
Our PB told us to wait 1.5 days after the application to start watering. Based on advice here and other stuff I read, I watered it as soon as I was able... Though I probably could have that night when I got home which was only a few hours after it was done. I waited about 13-14 hours after it was complete, as I watered it the next morning. Then the afternoon, and evening.
I'm doing 3x a day. Today I did a 4th which was a misting inbetween my afternoon and evening waters.

 

[DJFaninTN]

just water it. our FL sun will be drying that concrete out fairly fast. I watered mine at least twice a day if not more .. lol.

 

[MeowMeow724]

just water it. our FL sun will be drying that concrete out fairly fast. I watered mine at least twice a day if not more .. lol.

Yep! That's the truth!
I see you're in PC---- I am not too far from you, BTW!

 

[MinerJason]

Soooooo.... What does it turning light gray so fast during the day, mean?

It likely means the top layer of the shotcrete is relatively porous, so water is both getting sucked into the interior faster when you water it, and evaporating from near the surface faster after you're done watering. Could also mean that ambient conditions are promoting fast evaporation. Either way it's not something to really be concerned about. And it will get less porous as it hydrates /cures and calcium hydroxide and calcium silicate crystals grow and fill some of those small voids.

 

[MeowMeow724]

I got two of these sprinklers yesterday.
One going lengthwise, and the other going sideways.
I then put an adapter on my hose spigot to connect 2 hoses, so I can turn them on independently.
If I turn my spigot for the one going sideways, I can get the sides pretty well wet. I do have to go in the pool to soak sides just a *little* better because it misses a few small areas.
But, this is a MUCH better setup. Less messy, hot and sweaty for me! I can come home twice a day and keep it more wet this way, too. Thus, increasing my waterings to 4. I could get a timer, but I think I'm done spending $ for this very temporary need right now.. lol.
I wish I got this stuff sooner since I can only use this method until we do tile and coping!

I wanted to post this with pics to give others that come here searching for methods ideas ?

 

[MeowMeow724]

The gunite seems to be staying wetter on the surface, longer now.
Ever since they did the backfill and got dirt in the pool, the water also isn't disappearing from the bottom and is starting to accumulate quite a bit. I was considering taking a shop vac to get some out because another week of this and I'll have a pool before I have a pool! Lol

I'm also seeing white stuff coming to the surface in areas. Is that normal?

 

[ajw22]

The gunite seems to be staying wetter on the surface, longer now.
Ever since they did the backfill and got dirt in the pool, the water also isn't disappearing from the bottom and is starting to accumulate quite a bit. I was considering taking a shop vac to get some out because another week of this and I'll have a pool before I have a pool! Lol

I'm also seeing white stuff coming to the surface in areas. Is that normal?

Yes it is normal.

 

[Rattus Suffocatus]

I just watered mine until the waterline tile was done, right at seven days as much as I could with a garden hose. Worked out to be 4x a day or so. After the tile, the tile guy said "no" for 24 hours and be careful until 48 had passed. So I stopped at that point. It rained at least once a day at about the 36 hour point after tile, so it was about 4x a day until 7, and then once a day on 9, 10, 11. Seems fine. The tile guy and plasterer both said that 90% of owners don't do it at all and what I did should be close to the 100% strength chart. I would think with a sprinkler you'd actually be wasting water, but no big deal.

What that chart doesn't show is that the concrete continues to hydrate until about 100 years out. Primarily accelerating the curve at the beginning moves the strength way to the left. In really dry climates the first couple of days are critical at the surface as well so it doesn't turn into powder long term...