Floor Moisture Testing - Profit by Deception

It is an unfortunate reality that much of the "push-back" witnessed recently originates from those whose livelihoods are largely dependent upon people being confused, remaining confused and conflicted.

I found this reality during my stint of being a very well-paid "Construction Defects Expert" where the continuing conflict kept me really busy.

When I began this litigation portion of my career in 1985, I was optimistic and idealistic. Even with evidence to the contrary, I was convinced that accuracy and sharing of information would not only be welcomed, but embraced by those being victimized by misinformation.

I was wrong, and even today as I have been actively involved with litigation avoidance, the resistance and push-back has been ever increasing, but this time with a notable difference: inspectors, manufacturers, specifiers are FINALLY taking note as the information against this continuation of misinformation piles up and from a factual standpoint, now irrefutable.

About 25 years ago, I was on a panel of invited experts discussing floor moisture testing where I was the lone voice speaking out against using RH Probes specifically for measuring the moisture content of concrete.

After some discussion, when it came to my final comment as a panel contributor, I threw down a challenge that even to this day has not been accepted: I stated that to truly get to the crux of the matter, I am issuing a challenge to debate; with the caveat that the content cannot be modified or edited in any manner and that there will be no restriction to its distribution.

Profit by Deception

When the RH probes first came out, one of the bolder declarations of how much more "scientific" these were in comparison to the existing standard of calcium chloride testing was repeated in articles and presentations: "If current testing is so accurate, why are we still having moisture-related flooring failures?" NOTE: Moisture claims have since tripled...but do these folks ask this same question?

Either by ignorance or deception (at the end of the day, there is no difference in the final outcome to those who have been convinced by this false narrative), the Tramex moisture meter (electrical impedance) and all other meters were discounted as an accurate method of testing moisture within concrete, with its ONLY viability as a tool to determine where a RH probe should be set.

Anti-Science Claims

One of my chief complaints, for YEARS has been the compartmentalization of data. The segment of the concrete industry that is involved with concrete scheduled for flooring/coating and the flooring industry itself.

The flooring industry has accepted virtually ANYTHING that sounded plausible when it came to moisture testing, moisture control and moisture mitigation; otherwise the impossible claims of hydrostatic pressure, vapor pressure and "excess" RH would have NEVER been even considered, much less gain traction or become unenforceable requirements.

Why do I use the word "unenforceable"? because NONE of former and current standards were able to qualify the "limits" as written and required.

I remember back in the day when Joe Grady (RIP) and I were at one of the many conferences and began to exchange notes. We had virtually the same exact conclusions that the moisture limits given by the calcium chloride tests did NOT correlate under any statistic we could come up with.

The limit of 3.0 and 5.0 lb vapor emission had no correlation with moisture-related flooring failures. This is where pH and alkalinity came in.

A high pH had a much stronger correlation with "moisture-related" flooring failures, and a movement, again ill-conceived, targeted pH rather than alkalinity limits. This is likely due to pH being substantially easier to qualify than alkalinity; AND many "experts" did not know there is a difference between high pH and high alkalinity, once again pursuing a non-fact based path of least resistance, rather than delving into potential complexities.

Filling the Gap - Enter RH Probes

Frustrated by the then 1 billion per year "moisture-related" flooring claims, a "promising" technology was introduced that sounded wonderfully novel, exotic and "scientific", enter the RH probe.

Generally speaking, when someone has a notable conflict of interest, their involvement in standards development should be, at a minimum curtailed - this would/should raise a red flag, yet that didn't happen.

More disturbingly was the research used, with the limitations clearly stated that the research ONLY covered the initial mix water (water of convenience) that forms cement and makes the concrete mixture usable.

One of the limitations (curiously omitted when first being presented to others), was the fact that the presence of alkalinity would lower the measurable RH, even if the volume of water was unchanged. Another limitation listed during the initial announcement of the RH probe for the flooring market is these sensors had an accuracy limit of 10% to 90%. Yet, there have been no voiced, written or even discouragement against the misrepresentation that began at the outset and continues today; NO RH reading below 10% can be considered accurate, nor any RH reading above 90% can be considered accurate...if a number is beyond the listed capacity of the RH sensors, why was this overreach ALLOWED and even defended by some within the committee that APPROVED the RH Probe as a standard?

Wait - It Gets Worse (for RH "limit" claims)

Researchers, not understanding (since these facts have been non-prioritized) have jumped in and have used the current sensors for field studies. The results have been alarming and as beneficial as they have been deleterious towards the currently used sensors.

The Benefits

In the field, researchers have implanted the sensors and have discovered a prior unknown that may be common, if not a constant during the critical first 30 days of a concrete placement and curing. It was found that the concrete tends to self desiccate, particularly in the first 2-3 weeks after placement, even when using a curing compound and/or curing the concrete with water!

This self-desiccation (sometimes referred to as autogenous self-desiccation) can be extreme, where the RH within the first 0.75-1.0 inch of the concrete surface can be as low and 50-60%. Cement formation ceases when the RH is less than 80%!

Which brings us to another reality, who thought it was a good idea to target RH humidity limits, for a device designed specifically to ONLY monitor the drying progress of the concrete mix water at 70-75% RH?

Whoever decided that, is missing the critical point of cement formation is what DENSIFIES the concrete, but ceases at these "targeted" "upper limits.

Worse, people who are supposed to be concrete experts didn't catch that fundamental issue and continued to recommend RH probes AND the "maximum 70-75% RH, not just for new concrete, but for concrete that has been in service; which is ANOTHER caveat listed in the initial RH Study, it specifically excluded concrete that had been in service and even to the point of excluding concrete that had been rewetted!

The Problems

RH sensor manufacturers have CLEARLY defined the limitations of these sensors, yet it is common practice to accept numbers outside these parameters as some sort of tangible and accurate number...if the manufacturer says it isn't accurate, then it ISN'T.

and----It Gets Worse

Some researchers were disturbed by some unexpected anomalies during the field studies.

The first was that in several instances, the RH readings would get "stuck". This was discovered when they would remove the sensor, dry it, recalibrate it and then reinsert the sensor.

Once the sensor was reinserted, the changes in RH would then be measurable, but the sensors left in place did not reflect the changes in RH. NOTE: How many of you have EVER read this as a precaution, or even as a possibility?

It was not known how common this was or is, which prompted yet another study.

Several industry standard calibration solutions were used that would keep the RH at a constant level.

None of the four sensors currently being used aligned with the expected RH of ANY calibration solution.

NOTE: Since there seemed to be a consistent difference where sensors consistently measured higher than the RH constant and others slightly lower, if these differences are noted, the RH readings, even if not exact with the calibration solution can be of value.....BUT I have not seen ANY of these manufacturers give these variabilities and ALL use the same numbers as the calibration solutions, even as the study indicated NONE of them were as precise, even within the stated 10%-90% accuracy of these sensors.

As an example; one of the sensors measured consistently 2-3% higher than the sodium chloride calibration solution...if that was noted in their literature, the difference would be a non-issue and adjustments can be made accordingly; but they don't...so no one really knows what the actual measurement was/is or will be. After reading this, who is willing to accept that risk?

Impedance Meters vs Misinformation

Finally, if our respective industries would pull their collective heads out of the sand and start looking around, they would find information that is already well established and actually scientific, stop trying to reinvent the wheel and most importantly, start establishing accurate baselines and data interpretation!

Electrical impedance (designed specifically for the substrate, which is WHY no one should use a meter not specifically designed for the substrate to be tested) is NOT an imprecise method when measuring moisture in concrete. In other words, a wood meter measures wood, there are chemical in concrete that will create unexpected anomalies since wood material tend toward acidity and concrete tends towards alkalinity...a true apples and oranges scenario!

Further, electrical impedance methods are now being used as NDT (Non Destructive Testing) that are effectively replacing other methods, and in many instances MUCH more accurately than the destructive methods they are now replacing.

Electrical impedance is being used to calculated concrete maturity, corrosion of steel reinforcement, concrete density as well as moisture content. One such device was named Time Magazine 2023 Invention of the year (WaveLogix Rebel). Another is being used in Europe (Itek) where it has successfully detected early corrosion, creating proactive actions that would be otherwise impossible.

Cross Pollination - Looking for and sharing Data outside of a given Industry

I will give an excellent example of looking outside our respective industries: While doing research on potential reactions with calcium hydroxide (portlandite - hydration by-product of cement formation), I ran across a study in veterinary science where they were exploring the use of calcium hydroxide as a disinfectant. The main "problem" was the limited solubility of calcium hydroxide, particularly at room temperature since calcium hydroxide becomes more soluble with decreasing temperatures. The researchers found that (similarly to concrete research) high concentrations of sodium chloride will react with calcium hydroxide, discouraging penetration into concrete; which has continuously puzzled concrete researchers as to how and why the sodium chloride (sea coast structures, deicing salts) can penetrate into the reinforcing steel area.

The startling discovery was noted when they diluted the sodium chloride to a 1-3% concentration, this more than doubled the solubility of the calcium hydroxide, making it usable as a disinfectant.

Well, this can also help to explain how sodium chloride penetrates and why the penetration is so uneven...where it remains dilute, it can use moisture and calcium hydroxide as a vehicle of transport, whereas the more concentrated areas become somewhat "self-blocking".

THIS is an excellent example of the non-linear nature of many chemical reactions, where, as noted in some of my earlier articles, sodium hydroxide can be an anti-freeze at lower concentrations, only to become a freeze initiator at higher concentrations.

Each electrical impedance approach is modified for a particular purpose with the Tramex having successfully proven itself against gravimetric used as a control/baseline under field conditions and in extreme environmental conditions.

Outside construction, impedance meters are critical for sound systems/speakers...yet the hucksters pushing RH probes for an improper usage say that impedance meters aren't accurate or reliable....well, two of the RH experts "experts" have also claimed that a saturated alkaline salt will reach a humidity of 100% and that water vapor can and will carry alkalies and acids.

If and when other meters and methods can prove their efficacy, I will have no problem recommending them as well.

I am NOT an "inclusive" type..if it CANNOT PROVE claims and can potentially compromise what is best for my clients, I refuse to recommend it.