Concrete pool water fill rate

[EricQ]

I am looking for some advice on the rate to fill a concrete pool tank with water. I am working for a general contractor that is currently constructing a building that contains a commercial indoor pool.

The concrete reinforced pool is 20 000 x 25 000 in size with a capacity of 960000 liters/ 253605 gallons. The pool needs to be filled with water, and tested for leaks over a duration of 7 days. The time it takes to fill the pool is critical as it directly affects the construction schedule. The pool needs to get filled and the test started/witness before the winter holidays.

I have access to a 4" domestic water line that is roughly 8 Celsius/45 Fahrenheit, the concrete shell is indoor with the temperature around 18 Celsius/65 Fahrenheit.

Would filling this pool with cold water too quick cause a rapid change in the concrete pool shell temperature? Could this cause the concrete to contract and crack? If the water is heated close to room temperature would it increase the fill rate?

 

[hokie66]

If this is an in ground pool cast or shot against the earth, filling it soon, perhaps the next day after casting, will only assist in curing the concrete. But if it is a suspended pool or has walls which cantilever, then you should wait similarly to other structural work.

 

[EngineeringEric]

you cannot flow more water than you are getting. so you cannot change the flow rate with temperature (ignore expansion and all that as it is insignificant). The source water pressure matters more than the temperature, the pressure plus hose will tell you flow... or better yet, time how long it takes to fill a 50 gallon drum and use that proven method for your pool.

As for the concrete... as hookie said, is this pool over 7 days, over 28 days?

45 degrees is no colder for the concrete than when it was first made (an unconditioned building most likely). Based on that fact, i am not really concerned with shrinkage.

 

[EricQ]

The pool was formed, and has been backfilled on all 4 sides. There is a poured slab on grade surrounding the pools that is doweled into the walls. It was poured close to a year ago now. There are plenty of shrinkage cracks in both the slab and walls, wherever a concrete blockout was installed there are cracks. Every floor return in the slab, and every rope anchor in the walls where boxed out to be installed later.

The pool was cast in 2 pours. The slab was poured monolithically with no joints or sawcuts, just a keyway with a pvc waterstop. The walls were also cast monolithically with no joints. Both the slab and walls were wet cured for 7+ days. The top 4'/1200 of the walls were recessed to allow room for a 1"/25mm parging to be applied later. The parging has been completed and waterproofing is currently being applied ontop of the parging.

The domestic water pressure is quite high which is around 70 psi, the size of pipe can be reduced. I will time how long it takes to fill a drum and get a precise gallons per minute.

I was concerned about how the concrete would be affected, after typing this I am also considered how the parging material will react if there is a rapid change in temperature from the influx of cold water.

 

[hokie66]

How much crack control reinforcement does the pool have? Cracking is inevitable, but with enough reinforcement, about 0.6% Ag, the crack widths should be controlled acceptably. Where there are blockouts, there should have been additional reinforcement to control the corner cracking.

What type waterproofing? The interaction of moisture in the parging, with the waterproofing, would be a big concern. I trust this has been considered by the waterproofing applier.

I think your concerns about rate of filling and water temperature are misplaced.

 

[Ron]

Agree with hokie66...rate of filling for this application is irrelevant even with the temperature differential. I would be concerned that the design did not adequately accommodate the penetrations and the reinforcing required to mitigate cracking at these locations as hokie66 noted.

 

[EricQ]

So this pool has the potential to be filled at 480gpm/2800gph, meaning it could be done in roughly 9 hours. Would this be more of a concern if there was a greater difference in concrete/water temperature? I have heard horror stories of filling pools too quick with terrible outcomes, then again they are just stories.

The blockouts are located at the very top of the wall and are about 100x100x wall depth. I do not believe there is any added corner reinforcing.

The parging and waterproofing products are all part of a system by Laticrete which is designed to be used in pool tanks. It consists of 3701 modified mortar (base), 254 platinum (skim coat), hydroban (waterproofing). The hydroban waterproofing uses reinforcing fabric all corners and cracks before the membrane is applied.

 

[hokie66]

I have a lot of experience in pools, but have never heard any of those horror stories about filling. 9 hours sounds good.

If the waterproofing system works as intended, I doubt the cracks matter. The reinforcing fabric is a good idea.

 

[cvg]

rapid filling rarely causes any problems, but rapid drain does. I am a little concerned by your statement that it has been backfilled on all four sides. most pools are formed against earth and there is no retaining wall or backfill. this sounds like a unique design. You shouldnt have visible cracks in the structural concrete either, but I have to assume though that structure is adequate, whatever the design.