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ASA & ACI Guidelines Are Your Friend



Water Dampening - ASA - ACI Guidelines Are Your Friend - Grant Smith

The pictures in this article are ones that I took when I was called out to come look at a pool for remediation of a water loss issue. The homeowner had already contracted to strip it. The pool was demoed 4 weeks before he called me.

The porosity of the shell is evident along with the lack of coverage over the steel. This pool is a perfect example of why you should follow ASA and ACI guidelines. There have been some recent posts about shotcrete application being done incorrectly. There has been some push back about what is the big deal in not insuring that ASA and ACI guidelines are followed.

Just because you don’t have a structural crack does not mean your shotcrete was done correctly. Structural cracks are caused by under engineered pools in bad soil, soil settlement, and lack of rebar in ratio to concrete. Not caring about putting rebound or wall trimmings in the floor, the strength of the air compressor, the application of good nozzle techniques, the PSI of the concrete, keeping track of the concrete coming out of the truck and water curing all contribute to a porous and under strength shell.

Floors and coves need to shot first so rebound and trimmings can be shoveled out. Trimmings and rebound are not shot concrete and letting them fall on top of the floor that you just shot is not an acceptable practice. They need to be shoveled out. The proper PSI as mandated by the ACI for water vessels is 4,000 psi minimum.

There was a discussion on an earlier post about this (in Ask The Masters Facebook group). One person was stressing that it was the water to cement ratio that gave concrete it’s water tightness which is true. But let’s be field practical. Most ready mix plants or dry shotcrete nozzle men cannot get a perfect .45 W/C ratio.

The shotcrete crew will invariably add water while you are in the back supervising the shot. The higher PSI concrete will have less water in it to begin with so that helps keep the W/C in check. Plus the higher psi concrete just has more cement paste in it which also helps with the density of the concrete.

I can easily tell a 2500 psi shell versus a 4500 psi shell. The 2500 psi shell looks extremely sandy and soaks up water like a sponge. My shells are shot with 5,000 psi wet mix shotcrete. the shell is so dense that it actually rejects most of the colloidal silicate that I spray onto it. For the few hundred dollars it costs to raise up the PSI in your shell you are doing your client a favor. And if the client says your shocrete price is higher then educate them on why you the price is higher. Pretty simple. 250CFM air compressors for wet mix and 650CFM for dry mix to insure the density of the concrete.

The great thing about shotcrete is that it slams concrete paste and aggregate together which creates a more dense finished product. If you have ever done cast in place walls or piers you vibrate the concrete to make it more dense and and get out the air pockets and encapsulate the rebar. Shotcrete has the same effect.

Remember the denser the concrete the more water tight it will be. Water curing is essential to keep concrete hydrated while it is curing. By keeping the shell cool and moist it will retain more water that was in the mix to begin with which also help with a denser concrete. It will also help with shrinkage cracks. Shrinkage cracks occur because water evaporates to quickly out of the concrete. Water cure your shells for 2 weeks to a month.

I have seen a lot of engineers lately mandate a 30 day water cure but two weeks should be your minimum. Soaker hoses on a timer are always a good option. Don’t tell or let your client do it. It’s not their responsibility it’s yours!Once again I stress the first layer of water proofing is a proper concrete shell.

Grant Smith

Grant Smith is a featured Op-Editorialist for Pool Magazine and President of Aqua-Link Pools and Spas in Carlsbad, Calif. A former SWD Master, Watershape University faculty member, mentor and instructor; Smith is widely recognized as an expert and thought leader in the swimming pool industry.

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Swimming Pool Expert Witness

10 Steps To Avoid Irregular Pool Plaster



Avoid Irregular Pool Plaster Hydration With These Tips

The cause of irregular plaster hydration and streaking can be prevented with a little forward thinking.

1. Prepare the shell for plaster a few days in advance. Do not rely on the plaster crew to seal the shell on plaster day.

2. Chip out and repair every weeper and wet spot. Water flowing in, will be water flowing out.

3. Depressurize the pipes & remove ALL caps on the return lines and light conduits. Allow the water to completely drain out. Dripping water on fresh plaster will cause streaks.

4. Set the return fittings and seal around all of the penetrations with a cement material (non-shrink grout/hydraulic cement). Plaster is not waterproof (per National Plaster Council). Waterstop rings are highly suggested.

5. Using plaster to seal around penetrations can cause a visible halo effect, because of the excess thickness, white plaster patch or hydration variations.

6. Applying a bond coat to the entire shell will ensure the plaster hydrates evenly (yes, even new shells). The density of the concrete pool shell varies throughout, and so does it’s absorption of water. Bond coating will even everything out.

7. Fill the pool, starting from the deepest area first. Filling the spa first, may allow water to flow backwards through the plumbing and exit the pool lines. This will cause streaking on the walls.

8. An old gym sock taped on the end of the hose captures any sediment in the water and prevents the hose fitting from making any marks. This applies to plastic & brass fittings.

9. Do not use a water truck until there is a substantial pool of water in the basin. The cascading water flow can easily erode fresh plaster.

10. A pillowcase taped on the end of a large fill line can be used to capture sediment.

By following these simple steps, you can ensure you’ve done everything to guarantee an even finish appearance.

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Swimming Pool Expert Witness

12 Reasons To Use An Electronic Auto-Fill on Swimming Pools



Autofill Pools with a Jandy Levolor

Electronic auto-fills are slightly more expensive, but they offer important features required by edge vessels. They are far superior to float or bobber auto-fills for a number of reasons.

1. Electronic fills can activate huge fill lines for larger pools and water parks. The 24vac can activate any size irrigation valve. On a typical edge pool, I use a 1” fill line (compared to 1/4” on bobbers). A bypass line can provide for manual filling.

2. A maximum fill timer protects against catastrophic failures & overfilling. In the event there’s a pool leak, the auto-fill will cease. It will reset in 24 hours or when the power is turned off/on.

3. There is an activation delay, so minor waves from bathers or wind surges don’t cause needless filling.

4. There is no annoying hissing from the bather surges or waves.

5. There is not a large well of stagnant water for algae to grow in. By incorporating an overflow, a standpipe can periodically self-flush.

6. The activation delay eliminates frequent water hammer in the plumbing.

7. A 2” stand pipe is easier to hide in a beam. In fact with some ingenuity, you can incorporate an overflow line as well.

8. The fill tolerance is more precise – excellent for smaller or shallow vessels.

9. They are available with a high level sensor to activate edge pumps if bathers forget.

10. They can be placed on a relay and activated on a schedule. This is beneficial if the property is on a well, storage system or has an irrigation booster pump.

11. The fill line can be plumbed into a return line (non-edge vessels).

12. They are applicable to surge tanks of any depth. Bobber auto-fills are restricted by the depth of the well housing or the length of persons arm.

Sensor standpipes should be set 3-6 inches above the floor of the catch basin. The sensor tips should be set at the 12” minimum operating level. The fill line should ALWAYS be in the surge tank/catch basin on edge pools. Placing the fill line low on the end wall eliminates splashing & noise.

I’ve only had one issue in 20 years – a leaf got stuck across the probes and the unit failed to sense a low water condition. Now I place a perforated suction cover on standpipe opening to prevent debris entry.

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Grant Smith

Applying Shotcrete The Right Way



Applying Shotcrete The Right Way - Grant Smith

These are just two of the many examples of the proper way to apply shotcrete. Pouring or shooting the entire floor first or minimally shooting three feet of the floor and the cove.

This allows rebound and trimmings from the wall to fall on a hardened flooor and be scooped out. Keeping your hand from covering the top part of the nozzle allows the paste and aggregate to stay intact.

Covering the nozzle partially separates the past from the aggregate. If you follow at least these two simple rules that are mandated by the ACI and ASA you will be ahead of your competition in ensuring your client has a shell that will last.

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