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pH Testing - it is NOT being taught correctly
pH Testing Necessary, but Misunderstood
To ensure concrete moisture testing is accurate, it is imperative that pH testing be conducted to determine the concrete is clean, open and without any adhesives, coating, curing compounds, etc. pH testing should never be separated from “moisture tests” because without knowing the pH value, the moisture results could be VERY confusing, leading to incorrect diagnosis and/or subsequent repair/remediation.
What pH testing does
pH testing shows if the concrete is the proper pH, rather than the “improper” pH. Meaning that although there are written restrictions given by some manufacturers and to what constitutes a “safe” pH, these levels are for the most part, meaningless as the pH is at 9.5 or higher.
Fully “neutralized” concrete has a pH which is the same as limestone (which is a slightly alkaline stone). Neutral for water is 7.0, but that is actually acidic for concrete. In fact anything below a pH of 9 should be considered “acidic” for concrete.
Limestone has a pH in the range of 9-9.5. Limestone chemically is calcium carbonate. Concrete when fresh is alkaline 12.0-12.5 due to the natural formation of calcium hydroxide as “cement” develops. Neutralization occurs most commonly by exposure the the CO2 (carbon dioxide) in our air. When this carbon dioxide is absorbed by the moisture in concrete, it “carbonates” (carbon dioxide when added to water produces carbonic acid, same as that used to make sodas "bubbly")...turning into – calcium carbonate. So if any surface pH readings are less than 9, there is something on the concrete interfering with accurate testing.
It is not uncommon for concrete to have a pH as high as 13.3 (extremely alkaline), which is mostly caused by sodium hydroxide (and to a lesser extent; potassium hydroxide) that is a natural by-product introduced during the sintering process. In the last few years, the sodium hydroxide content has increased (created by environmental concerns that require the “recapturing” of flue gases) by as much as 400% percent in some cement mixtures, creating problems with alkalinity that were not as much of a concern in prior years. This is where it gets confusing: sodium hydroxide is highly “buffered” meaning it maintains a high pH through a HUGE range of concentrations.
At 1% concentration, the pH of sodium hydroxide is about the same as fully concentrated calcium hydroxide – pH of 12 (which can lead to misidentification of elements if analysis is not done), at 10% - pH of 13, and holds this high pH until almost fully concentrated, when the pH value goes to 14. Since fresh concrete has a range of 12-13.3, concentration of the much more damaging sodium hydroxide is unknowable with a simply pH test. At a 10% concentration, likely is not damaging to a coating or adhesive, but at concentration levels higher than 20% almost assuredly damaging and in higher concentrations, the effects can be devastating to a floor assembly.
Complications of pH Testing
It is common for specifications to state that the flooring installer, a “certified test agency” or possibly even a laboratory conduct moisture tests. In truth most, if not all these agencies are not sufficiently skilled nor taught what pH values mean and many “professionals” think that pH and alkalinity are correlative - they are NOT!!!
To my knowledge, this information is NOT taught by any of the private schools or professional organizations as to how to properly teach moisture and pH testing. Until the facts are known, certification of such individuals is of suspect value. This may sound harsh, but it IS the reality of where the flooring and even concrete industry sits at the present time.
To ensure concrete moisture testing is accurate, it is imperative that pH testing be conducted to determine the concrete is clean, open and without any adhesives, coating, curing compounds, etc. pH testing should never be separated from “moisture tests” because without knowing the pH value, the moisture results could be VERY confusing, leading to incorrect diagnosis and/or subsequent repair/remediation.
What pH testing does
pH testing shows if the concrete is the proper pH, rather than the “improper” pH. Meaning that although there are written restrictions given by some manufacturers and to what constitutes a “safe” pH, these levels are for the most part, meaningless as the pH is at 9.5 or higher.
Fully “neutralized” concrete has a pH which is the same as limestone (which is a slightly alkaline stone). Neutral for water is 7.0, but that is actually acidic for concrete. In fact anything below a pH of 9 should be considered “acidic” for concrete.
Limestone has a pH in the range of 9-9.5. Limestone chemically is calcium carbonate. Concrete when fresh is alkaline 12.0-12.5 due to the natural formation of calcium hydroxide as “cement” develops. Neutralization occurs most commonly by exposure the the CO2 (carbon dioxide) in our air. When this carbon dioxide is absorbed by the moisture in concrete, it “carbonates” (carbon dioxide when added to water produces carbonic acid, same as that used to make sodas "bubbly")...turning into – calcium carbonate. So if any surface pH readings are less than 9, there is something on the concrete interfering with accurate testing.
It is not uncommon for concrete to have a pH as high as 13.3 (extremely alkaline), which is mostly caused by sodium hydroxide (and to a lesser extent; potassium hydroxide) that is a natural by-product introduced during the sintering process. In the last few years, the sodium hydroxide content has increased (created by environmental concerns that require the “recapturing” of flue gases) by as much as 400% percent in some cement mixtures, creating problems with alkalinity that were not as much of a concern in prior years. This is where it gets confusing: sodium hydroxide is highly “buffered” meaning it maintains a high pH through a HUGE range of concentrations.
At 1% concentration, the pH of sodium hydroxide is about the same as fully concentrated calcium hydroxide – pH of 12 (which can lead to misidentification of elements if analysis is not done), at 10% - pH of 13, and holds this high pH until almost fully concentrated, when the pH value goes to 14. Since fresh concrete has a range of 12-13.3, concentration of the much more damaging sodium hydroxide is unknowable with a simply pH test. At a 10% concentration, likely is not damaging to a coating or adhesive, but at concentration levels higher than 20% almost assuredly damaging and in higher concentrations, the effects can be devastating to a floor assembly.
Complications of pH Testing
It is common for specifications to state that the flooring installer, a “certified test agency” or possibly even a laboratory conduct moisture tests. In truth most, if not all these agencies are not sufficiently skilled nor taught what pH values mean and many “professionals” think that pH and alkalinity are correlative - they are NOT!!!
To my knowledge, this information is NOT taught by any of the private schools or professional organizations as to how to properly teach moisture and pH testing. Until the facts are known, certification of such individuals is of suspect value. This may sound harsh, but it IS the reality of where the flooring and even concrete industry sits at the present time.
Replies to This Discussion
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Permalink Reply by Stephen on -
Well Bob thats just darn scary. What can we do about that lack of education and with all these new admixtures.
Your making me afraid to adhere anything to concrete! Are you saying one should grind the surface of the concrete prior to performing a ph test?
Does that not change the surface structure since I would not be grinding the entire surface of the concrete unless there is some sort of sealer on it?
And as it applys to a moisture dome test, why are we required to grind the surface prior to testing if we are not grinding the surface to install said flooring. Is this not giving us a false reading since grinding the surface reveals a totally different surface structure and opens the valve on mosture movement through the surface of the concrete?
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Permalink Reply by Bob Higgins on -
Selva mentioned that he'd like to start something and I think that would be a great idea...I gave a seminar at one of the major universities, with one of those in attendance, being one of the most knowledgeable people in the Federal Transportation Research Board..they were completely blown away by the information I provided and when it was checked out..I was 100% correct.
I am setting up examples of how these can be misread and how temperatures alone can create difficulties. Yes...temperature can dramatically affect the pH reading of the same exact spot..depending on what the prevailing temperatures were during and preceding the test.
I've seen demonstrations by reportedly knowledgeable inspector and testing agencies where they felt a pH on a concrete surface of 7 to 8 was good..WRONG answer..what it means is any moisture testing they did, was incorrect!
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Permalink Reply by Stephen on
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I am ready to drive to San Diego. But I am booked till after Christmas so how's about February?
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Permalink Reply by Stephen on
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Oh sure have the class back east like all the other ones. Not fair, not fair!
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Permalink Reply by Woodie to you on
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Wfca has been on board for most of these classes have they not?? The scholarship money from them goes far in these affordable classes that offer alot if you are interested in learning the whys and why not's that are noticeably absent from the industrys accepted and over priced/outdated classes.
Not to mention what you learn from the attendees,(some of them anyway) which is just as important and meaningful.
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Permalink Reply by Bob Higgins on
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WFCA and many others only know what they are given.
Rightly so, they rely on experts from these other fields to give them factual information, which in turn they use to disseminate information to their membership and the flooring industry. I do NOT fault these organizations for doing this...I do fault however, those who give such information; and when new information showing the earlier information was indeed inaccurate and ignored, it shows a flaw in the hierarchy that allows us to again and again be mislead..intentionally or not..the end result is still the same.
I wrote the majority of the technical portion of the white paper, published by the WFCA, and with all good intentions, I am still proud of everyone who contributed to both sections of that paper. Unfortunately it has been misused and misinterpreted..and frankly, it would be wonderful to have that committee reform to update and basically act as a gatekeeper for much of the information that comes out. THAT would be a full-term job unto itself (my wish list/rant..sorry).
Much of what I understand now..wasn't understandable based on information I was given earlier. It is a difficult lesson to learn, but I've stopped relying upon others for information germane to my consulting practice...causing me to re-learn and in many other cases to "unlearn" the information I've been given.
In concrete research, most, if not all information on hydroxyl ions (the most reactive and aggressive alkalis) in concrete were lumped up in one convenient pile..disregarding basic fundamentals that make such lumping up - inaccurate and downright dangerous, leading to incorrect testing, confusing results, and even standards based on such errant information.
I will give an example..with names changed to protect the innocent of a hard lesson I learned 15 years ago about "standards".
One state decided to completely overhaul their requirements and standards for products considered acceptable for use on concrete highways, bridges, etc.
After a near complete gutting of the old standards and proudly announcing they've stepped into the present and ready for the "new technologies", there were several products already in use and basically they decided to test these products, which in turn would act something of a baseline (and for curiosity sake), using the new standardized tests on these products.
One in particular had been used successfully for decades and in my opinion..a VERY good product. Well, they conducted the new tests on this product..it failed the tests miserably! How could that be? so apparently they re-ran the tests, contacted the manufacturer to see if they may have received a defective batch, etc.
Turns out the product failed and kept failing..yet iperformed brilliantly in the field.
So did they trash the new "standards" now pretty much proven to not accurately reflect what happens in the field?
Nope..they simply grandfathered the failed product in and kept the new standards.
Unfortunately this happens more often than we'd care to even believe..and sometimes the results are phony'd due to pressures from the marketing depts, deadlines, etc.
In a survey conduct which appeared in an issue of Industrial Chemist Magazine (I believe back in 1988)...over 30% of the respondents admitted to faking test results due to such pressures...
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Permalink Reply by Stephen on
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Looking for an update there Lee.
Plus I would like to ask Bob a question about that ph meter that has been out for several years....does it work well and is it reliable?
Oh also age of ph tape, does it matter? -
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Permalink Reply by Bob Higgins on
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Good morning Stephen..not knowing the brand of pH meter..I can't really answer that question...most pH meters are fairly reliable..but there are methods of use that each meter has that has to be followed to ensure accurate information.
Since most pH papers have organic dyes that create the color changes when exposed to the different pH ranges..it makes sense that these would become less effective as they age..but no one, to my knowledge has ever assigned an expiration date to any of these..in fact, when you first purchase them, how long have they been sitting around, are there some types of dye reactions that fatigue quicker than others?
That question you posted gives great food for thought Stephen!!!
and remember everyone..pH does NOT measure concentration..those measurement are non-correlative for the most part...
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Permalink Reply by Stephen on
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Mornin Bob, thanks for responding so quickly.
This meter is most widely available round these parts. Know of a better one?
http://www.amazon.com/dp/B00023RYQ8/ref=asc_df_B00023RYQ8989638?smi...
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Permalink Reply by Stephen on
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Choppy, here is what I know which seems to be not so much these days. Your supposed to lightly sand the surface of the concrete to remove supposed sealers and contaminates, vacuum and then apply a small puddle of distilled water on the surface, agitate the water on the concrete slighty and stick in the ph strip. No holes!
Thats where I kinda disagree with the newer rules. If your going to glue your wood or what ever flooring to be on the surface of the concrete that has no sealers or what ever contaminates that would hinder adhesion, and you have tested that surface succesfully to reveal no contaminates...why sand the surface? IMHO sanding of the surface is going to give you a totally different reading than the original surface your planning on adhering your floor to.
I have not tested this theroy but it would seem logical that the surface underneath the cream surface would give you a totally different reading...presumably a false positive or higher reading than the original surface reading.
Does that make any sense? lol
Same goes with calcium chloride tests, ie opening the pores of the surface. You know some ppl may grind down to the aggregate. Maybe Bob will chime in and shoot my theory down.
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Created by Steve Simonson Nov 6, 2008 at 10:58am. Last updated by Steve Simonson Nov 6, 2008.
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