FACT and REALITY
Longstanding cement and concrete science has established that calcium chloride-in acceptable quantities-is a primary cause of discoloration in cementitious surfaces, particularly when steel troweled. Further, the Portland Cement Association research performed in 1966 described that when the ratio of cement alkalis to chlorides was low, a light spotting discoloration on a darker background resulted. The white cement used in swimming pool surfaces is a low alkali cement.
These surface discolorations were permanent and such discolorations would become more pronounced with increasing chloride levels.
These cement researchers also indicted any practice that skewed the surface water to cement ratio. The water to cement ratio is the most important factor in determining surface durability. All cement and concrete authorities specifically recommend against adding water to tools or surfaces during finishing operations, or troweling bleed water back into the surface. It negatively impacts the surface and is known to cause a variety of surface defects and problems in addition to the ones described in the 1966 research.
Years later, starting in 1999 and continuing into 2011, another generation of prominent cement scientists independently examined spotted swimming pool plasters, and determined that some of the same original factors caused similar problems, and certain others, in swimming pool surfaces. They also determined that aggressive water conditions DID NOT cause the problem. These scientists pointed to three of the same variables as determined by the cement and concrete industry as causative factors-use and abuse of calcium chloride admixtures, excessive hard troweling of the surface, and applying water to tools or surfaces during finishing operations (skewing the surface water to cement ratio). Sound familiar?
When confronted by these facts, the NPC claimed the original 1966 cement research did not apply somehow because gray, not white, cement was used. The NPC ignored the fact that cement and concrete industry literature described that even greater attention to such details was required when white cement was used. And, considering that swimming pool plaster is designed to be immersed in water, the durability and non-permeability of that surface is even more critical!
With the exception of a higher iron content that is found in gray cement, the chemistry of cement is consistent, and does not change based upon the application. In fact, swimming pool plaster is a much richer cement mix, which makes that cement chemistry-and the things that negatively affect it- much more important. But, again the NPC said none of that original cement research applies to us. (Is there some magical change in white cement chemistry when it is used in swimming pool applications?)
As to the modern cement research that specifically and directly linked the same factors to causing spotting and certain other plaster defects in swimming pool plaster, the NPC buried its head in the sand, and pretended that research never happened. It is still happening today, at the expense of the industry and its consumers.
In 15 years, the NPC has never tried to refute the eminent scientists that told the industry that improper plaster workmanship was to blame for the spotting problem. They ignored, redirected, and did everything possible to avoid meeting that science head on. Why? Because it is a battle they cannot win. Dr. Boyd Clark, Mr. Niels Thaulow, (chemical engineer and petrographer) Ms. Laura Powers, (microscopist and petrographer), Dr. Michael Silsbee, Dr. Mengesha Beyene, and Mr. Ron Sturm (petrographer) are a dream team of some of the finest cement scientists in the nation. Go ahead, tell me how each and every one of them failed in their examinations or misinterpreted data, and made invalid conclusions.
(The irony of this is it was originally the NPC's idea to use these modern cement researchers to determine once and for all, the cause of spot "etch". On May 15, 1999, the NPC Board and its research committee, agreed to engage two of the most prominent cement laboratories, Construction Technologies Laboratory (CTL) and the RJ Lee Group to examine spot "etched" plaster and find out what caused it. That research never happened.)
To date, NPC has never refuted these scientists and invalidated their conclusions. And those scientists’ and laboratories conclusions are completely consistent with the standing science of the cement and concrete industry. Frankly, I don’t think the NPC can refute them, and that may explain why the NPC does everything possible to pretend that these scientists’ research doesn’t exist.
And, for a few reasons, the swimming pool industry cannot accept the NPC argument that their own Cal Poly research somehow refutes these scientists. First, to invalidate “our” cement scientists’ position, you have to specifically identify exactly where the scientists made mistakes-in their examinations, in their methodology, in their observations, and most certainly in their conclusions. Second, the NPC’s Cal Poly research DID NOT prove anything that was claimed, and critical review exposes it as a research embarrassment.
FICTION: and THEORY
For those of you that want to believe the NPC’s claim that their Cal Poly research "proved” aggressive water conditions" (and not plaster workmanship issues) caused spot etching, consider the following. In September, 2004, the NPC and Dr Damien Kachlakev, their principal researcher at Cal Poly, claimed their Phase One study concluded that “water chemistry is the most important factor in the spot etching of swimming pool plaster.” (Pool and Spa News, September 2, 2004)
But I am betting you didn't know that 6 months later, in a written report on the same research to the International Cement Microscopy Association, Dr. Kachlakev stated that they did not link water chemistry to causing spot etching-primarily because they had botched the water chemistry maintenance in the research project so badly as to invalidate the study:
“While the observations from this study are useful in showing different stages and mechanisms of SA [spot alteration, or spots on the plaster surface] in pools, they do not link SA to a specific set of construction practices or water chemistry conditions.”(bold and underline emphasis added)
So, the Cal Poly study did not link spot etching to water chemistry conditions, which clearly contradicted the earlier statement in the Pool and Spa News. But, neither the NPC nor the professors ever advised the swimming pool industry of this very important change of conclusion, or admission of research failure. I don't know about you, but I can't imagine anything more newsworthy-or embarrassing. But what is most disparaging, is that both the NPC and the professors continued to claim the "aggressive water conclusion" to the swimming pool industry, and actually used this fatally flawed research as the foundation for subsequent research-all of which attempted to disclaim any workmanship issue, while blaming water chemistry.
All of that certainly does not measure up to the monumental task of invalidating either the cement scientists’ conclusions or the standing science of the cement and concrete industry.
So, what do you think? I look forward to your comments, and we’ll get to Part Two in a few days.
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