Plaster issue, need advice

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The builder will be coming by tomorrow to take some pictures. I will ask for the information you suggested regarding the composition of the plaster. I will also pick up some sandpaper tomorrow and see if that makes any difference.
I have not heard back from NPT. I will wait and see what happens with the builder before trying to contact them again.

Thanks again for your insight. I will update again as things proceed. It's a relief to know that it isn't my fault with chemistry and maintenance. It is my first pool, but we have been very diligent in maintaining and cleaning it. With all the denial coming from the builder and plasterer I started to believe that maybe it was something I did.
 
Just met with the PB.

I tried explaining everything you've suggested (calcium chloride, or filling issues). Their reply was, "Who said this?" "What kind of certification do they have?"

Apparently years of experience owning a pool count for nothing in their mind. So my question now is does anyone know how you go about contacting someone who is certified in these matters? I also found out that the plaster was NOT from NPT as I originally thought. All my other products came from NPT. I was told today that it was from Universal White Cement. I have already reached out to them, just waiting on a response.

I would get a second opinion on the plaster, but there is only one company that does it locally. The next closest is Vegas. Does anyone recommend a plaster guy in Vegas that may be able to look at the pictures and offer an "expert" second opinion?

Thanks again, I don't know what I'd do without the support.
 
You can tell him that I have 40 years of experience in the pool industry, and I am a former pool plasterer.
Share with him the followings references regarding discoloration of cement surfaces:

“Calcium chloride causes an increase in drying shrinkage, discoloration, (darkens concrete), and scaling (flaking, spalling) potential.”
“Design and Control of Concrete Mixtures,” Portland Cement Association, Thirteenth Edition Pg. 66)

“Variations in water or cement content can have a considerable effect upon the color of concrete (see Fig. 11). A low water-cement ratio paste is almost always darker than a high water-cement ratio paste made with the same cement (Greening and Landgren 1966).” EB217 White Cement Concrete Portland Cement Association 2001 p. 9

“Changes in the w/cm of concrete mixtures can significantly affect color. Such a change can result from localized variation in the concrete’s water or cementitious material content…” ACI 302.1R Guide for Concrete Floor and Slab Construction Section 11.9 – Discoloration

“The magnitude and permanence of discoloration increase as the calcium chloride concentration increases from 0 to 2% by mass of cement. Discoloration can be aggravated by high rates of evaporation during curing…” – ACI Report on Chemical Admixtures for Concrete 212.3R-10 5.7.1- Discoloration of flatwork (Note that this discoloration happens at levels between 0 and 2%. When calcium chloride is added at levels exceeding 2% the effect is much greater.)

And the National Plasterers Council's 7th Edition of the Technical Manual states that the addition of calcium chloride can alter and darken pool plaster, pg. 12 and 13.
And suggests that no more than 2% calcium chloride should be added. And the manual also states that adding too much water while troweling is also detrimental to pool plaster.

All of the above information is consistent with discolorations in your pool. There is no evidence that unbalanced water causes white plaster cement to turn dark gray.
It is apparent that the PB/plasterer is trying to avoid responsibility.
 
I will forward all the information to the PB.

I just got off the phone with Universal White Cement. I have to give credit to their customer service. They were in contact with me within a couple hours. They have already reached out to the installer. I sent them the pictures and things seem to be moving along. Awesome customer service!
 
Here is how I see this "white" quartz plaster turning "gray" problem.

1. The start-up and ongoing water chemistry conditions should always be considered when investigating most plaster problems, and for this case, the OP indicates that the pool and tap water is/was balanced. Therefore, that establishes a fairly reasonable basis to exclude "out-of-balance water" as a probable cause. And graying of the plaster itself, rather than a gray stain or deposit (which still needs to be verified by the OP by sanding a small area), makes it more likely that water chemistry is not the cause of graying. And further, aggressive water does not cause white plaster to turn gray, and especially in unusual patterns and areas.

2. According to the weather almanac, the temperatures in St. George Utah in or around January 5, 2016, was from 40 degrees in the morning and up to 50 degrees in the afternoon. The OP stated that the plastering job was completed in 4 to 5 hours. I believe that the plastering contractor probably added a cement hardening accelerator to be able to finish the plastering job within that time frame. Otherwise, I believe it would have taken more than 8 hours to complete. The OP stated that he heard a crew member indicate that they had run out of "calcium" during the job. That most likely indicates that "calcium chloride" was being added to the plaster mix, and that they didn't bring enough to compensate for the amount that they were adding.

3. The addition of Calcium chloride is well-known for causing the graying of both gray and white cement. It also causes shrinkage cracking when too much is added. It very well could be that the gray areas in this pool are due to excess calcium chloride being added, and the white areas are where NO calcium chloride was added. Calcium chloride affects the hydration (hardening) rates of the various types of cement compounds creating lighter and darker effects. This is why I asked that the plaster contractor should state if calcium chloride was added and how much was added to each batch of plaster material.

4. It is also well documented that late hard troweling also contributes to the darkening or graying of white (and gray) cement products, which could also be an issue with this plaster job and contributed to the graying discoloration.

5. It is well documented that the sprinkling of water while troweling can cause a difference in water-to-cement ratios on a cement surface and create "light and darker" areas on the cement surface. Certainly, other water filling and splashing issues can also affect the cement hydration process and therefore, cause differences in white cement shading or graying.

6. An analysis of how much calcium chloride was added to the plaster mix can be easily performed, and only costs about $100. I believe that step that needs to be taken in order to learn what may have occurred to have caused the graying. Generally, less than 2% calcium chloride should be added to white cement products. Pool plaster contains about 35% to 40% (white) cement and the rest is an aggregate that doesn't get involved with discoloration. Concrete flatwork, such as sidewalks and driveways, and pool plaster are very similar and are applicable to the same discoloring and defective issues due to improper practices.
 
It is important to remember that although it is recommended not to exceed 2% calcium chloride that does not mean that every pool that does will stain and discolor. Excess water while troweling can be a problem, but the use of a small amount of lubricating water is a common and accepted practice. The foreman saying that they ran out of calcium yet the floor is still discolored is interesting. Normally the walls are shot first then the floor last, if calcium was the cause the last area shot without calcium would be unaffected. I would wait to hear from Universal Cement, and try the sand paper as mentioned above.
 
I ran to Lowes this morning and got the sand paper. I used a 400 grit wet/dry sand paper and rubbed it on part of the wall for a minute. There appeared to be no change in the appearance of the plaster. I didn't use much force, just a light rub. If I should use more force let me know, but I wanted to be conservative and start out light.

The discoloration on the floor in minimal compared to what you see on the walls. The floor is mostly swirl marks, like arches from the troweling.

Still in contact with Universal. They're waiting to hear back from the installer.
 
Actually, adding even amounts less than 2% of calcium chloride to white pool plaster mixes will cause a minor amount of gray or off-white discoloration. That is because a small amount of calcium chloride will still react with and retard the hydration of some of the tricalcium aluminate compound and the very small amount of tetracalcium aluminoferrite compounds in cement, which causes a minor amount of uniform graying and off-white color. That is confirmed by the quote above in my previous post (ACI Report 212.3R-10)

The reason that some believe that there are sometimes "no discoloration" when calcium chloride is added to pool plaster is due to the nature of the discoloration. When the slightly off-white or gray discoloration is uniform and very consistent throughout the pool, it will not be noticed. That happens all of the time. As long as the troweling process is done perfectly, the slight and uniform darker color hue will not be noticed. But when imperfect troweling occurs, and we are talking about extra wet or water troweling and extra late hard troweling, the result is a visible and distinctive contrast between pure white and off-white or slightly gray color.

Even pool plaster that contains no calcium chloride can also have an uneven or blotchy contrast looking plaster surface. And that is solely due to poor troweling practices. The OP of this pool may see this effect with his observations of the bottom of his pool. However, further investigation into this discoloration problem is needed before a final conclusion can be made.

My experiment performed many years ago shows how discolorations can occur. How White Pool Plaster Can Turn Gray

Lastly, I agree that using a very small of "lubricating water" will not normally cause significant discoloration contrast problems. However, let's understand that while the pool plastering trade may say that wet troweling is an accepted practice, the concrete flat work industry does not. ACI and PCA both advise against that practice, and for good reason when the desire is to produce aesthetically pleasing and consistent looking surfaces.
 

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You quote the NPC technical manual, 7th edition, with regards to calcium use the dismiss their view of lubricating water? By the was the Eight edition of the NPC technical manual is out now. I was just trying to convey that to say calcium in excess of 2% is the problem is probably not the most effective argument especially since the percentage used is unknown at this time.

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I can vouch for excess calcium causing discoloration. I've found quantities in excess of 5% to consistently create color variations.

I'm not sure how careful your crews are with measuring ingredients but I know the ones I've encountered are less than scientific in their additions. I wouldn't be surprised if each batch varies from 2-10% calcium and water content from 0.4-1.2:1 cement ratio.

You can see the obvious results here:



The top three had calcium added at 2%, 5%, and 5% with 1:1 water/cement ratio.

The bottom sample had no calcium added and was 0.45:1 water/cement.

I'm experimenting with a plasticizer now that will not only replace all of the calcium chloride needed but a good portion of of the excess water needed for a mix to be workable as well. I'm hoping to produce a much more consistent color (especially greys and blues) while still maintaining a 4-5 hour timeframe from application to final troweling.
 
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