Science without Context = Nonsense

I read different reports and studies on a near weekly basis and I end up shaking my head at certain "conclusions" being made that are either NOT supported by the results in the very same report, particularly when laced with modal verbs such as "may", "can", "usually", "should", "could".

Yet when paired with suggestive verbiage, these "might-be's" become "fact".

Worse, many of these "conclusions" either lack context or simply use truncated data, which is a particular pet-peeve of mine.

NIST State-of-the-Art Report on Concrete (1999) - Context and Truncated Data

There is some incredible information within this report and I HIGHLY recommend anyone interested in this subject obtain their own copy.

That being said, this report was an eye-opener for me since it inadvertently presented the ever-evolving narratives facing the industries where concrete is an important building component.

I and many others were told continuously if concrete was "properly cured", curling, cracking and warping can be "minimized". Unfortunately, "minimized" is a very dynamic term...minimized as compared to what? That part is never qualified, much less quantified.

The conclusions, even though this was well-before CKD and other recent modifications to cement (and NOT including the emerging use of limestone cement) were introduced, adding other complications to an already unsettled direction.

This state of the art report concluded and is re-affirmed by multiple concrete organizations that concrete that doesn't curl, warp or crack is an unrealistic expectation, irrespective of the curing techniques employed.

There was a section where alkalinity was addressed and brushed aside as a non-issue, even as the conclusions, although accurate within a very narrow context that was NOT addressed within this report.

It was stated that sodium hydroxide acts as an antifreeze within concrete. THIS is a great example of using truncated data that ends up being more misleading than helpful.

In low concentrations, even upwards of 20%, sodium hydroxide does indeed act as an antifreeze, dynamically. The characteristics change dramatically within the 1% to 20% range, which in and of itself isn't alarming.

HOWEVER.....as sodium hydroxide becomes more concentrated, particularly in the 40% range and higher, sodium hydroxide becomes a freeze-initiator!

It goes in the exact opposite as what is presented in the NIST Report!

At 40% concentration, the freezing point of the sodium hydroxide and water solution is now at 59oF!

and....it gets worse......the water contained in this solution no longer behaves in a predictable manner and NOTHING like water would behave in an open environment, yet nearly every test and study is built around the premise and predictability of water in an open environment!

As the sodium hydroxide increases in concentration, which is EXACTLY what happens when drying techniques are employed, the freezing point of the water in this solution continues to climb, but NOT in a linear fashion!

To add even more complexity, as sodium hydroxide increases in concentration, the RH continues to decrease, even if there is a significant volume of liquid water present! If the sodium hydroxide/water solution becomes concentrated to 60%, the chemically induced "freeze point" of the water is now at 125oF. That is NOT a misprint!

If this dynamic is applied to drying techniques, it easily explains the confusing "bounce" the drying professional will experience as soon as the drying efforts have stopped and an otherwise inexplicable increase in moisture occurs.

The dynamics include rapid moisture absorptivity of the alkaline solution, the lowered RH and that the water behaves in a manner of being chilled (escalating resistance to moisture removal) rather than warmed during the drying process.

Without understanding ionic dew point, critical humidity threshold, RH of saturated salt solutions and how this relates to concrete, these results will continue to be very confusing.

This confusion extends into moisture testing. Standard methods conforming to ASTM F2170 and ASTM F1869 WILL be dramatically altered in the presence of alkalinity, particularly when the alkalinity becomes concentrated.

A 30% concentration of sodium hydroxide and water will produce a reciprocal RH of 63%, irrespective of water volume! Using the unsupportable "voodoo logic" given by overenthusiastic RH Probe (ASTM F2170) promoters, this means this saturated concrete is dry!

Additionally, a lowered RH will slow the moisture uptake of the calcium chloride (F1869) method, potentially giving an "all clear" signal that moisture isn't a concern. In an odd, but out-of-context reasoning, that is an accurate assessment because it will be the alkalinity that causes the damage, NOT the moisture!

Logic Trail

Many years back, I forwarded the hypothesis that concrete can initiate surface ASR during the curing process.

I was derided and mocked since everyone knew that all ASR was a "time-dependent" chemical reaction that took many years to develop.

I argued that the lighter, most susceptible aggregate (which also tended to be amorphous) would concentrate towards the surface, and as the concrete cured, particularly with plastic sheeting. NOTE: As a demonstrable difference between an amorphous silica and a crystalline silica, I have used silica gel and decomposed granite, mixed with varying concentrations of sodium hydroxide to illustrate the speed (and differences in speed) in which the silica gel will dissolve, even as some types of granite resist dissolution indefinitely. THAT is a simplistic example of ASR formation, as it is the susceptibility of the lighter amorphous silica to dissolve.

Turns out, this DID happen, DOES happen and was even coined with a term within a concrete magazine article. This confirmation helped me to build the information and knowledge base that confirms the top surface of concrete IS distinct from the remainder of the concrete, and now proven in dozens of studies from around the globe. Since alkalinity tends to concentrate during the curing process, it stands to reason the RH would also drop! THIS is why curing techniques developed back in the early 1900's are no longer applicable, yet there is an obstinate clinging to "how we've always done it", even though the concrete IS different from way back when.

This graphic is an excellent example of the influences (or non-influences) of ambient conditions. In agreement with field studies, the top one inch of the concrete self-desiccates and falls below the 80% threshold needed to produce cement within a 2-3 week time period. Even as this graphic lacks a 2 inch measurement, the difference between one inch and three inches is dramatic.

NOTE: This graphic depicts laboratory conditions. In less than ideal conditions, particularly in elevated temperatures, the differences would be even more dramatic.

If You Can't Beat em, Change the Emphasis!

In either a very deviously clever, or incredibly ignorant move, the RH proponents have simply by-passed the alkaline issue by burying the probes well past the gradient portion of the concrete (see above graphic), which is the top 19-25mm (0.75-10 inch) of the concrete surface.

By-passing the gradient portion also by-passes the highest alkalinity portion of the concrete as well as comfortably nestled in an area that changes very little in either RH or moisture content.

In a distinct contrast, the gradient portion of the concrete is responsive to ambient conditions.

These differences were inadvertently admitted to within a slide presentation given by one of the enthusiastic RH Probe promoters, where it was shown that there were "deficiencies" in the ASTM F1869 method since warmer ambient conditions will produce higher moisture readings even though the moisture content itself hadn't changed. SERIOUSLY?!?!?!?!

That is a tacit admission of the presenter NOT understanding dew point...warm moist air plus a cool surface is the combination that creates surface condensation (dew point).

If alkalinity is present, dew point can STILL occur even when atmospheric dew point isn't possible. THAT is what is termed ionic dew point!

Easy illustration/example is the standard sodium chloride/water calibration solution. If the RH is higher than 75% (not the 100% required for atmospheric dew point), condensation WILL occur. I like using sodium chloride as an example because ANYONE who has used a moisture testing device of any sort is likely familiar with this.

As long as the sodium chloride is at or near saturation, the measurable humidity of the immediate air space will remain at 75% RH.

So, if concrete pores are full of salt water and the RH measures 75%, according to manufacturer warranties, that concrete is dry and safe to install a flooring material. Yes, it is every bit as ridiculous as it sounds, yet really smart people have been duped, simply because they lack the skill set to investigate the veracity of such "expert opinions"!

There is NO Such Thing as a Floor Failure "Caused" by High Humidity

First off, the variable "humidity limits" are unknown and unenforceable within a warranty since the RH Sensors traditionally used are NOT accurate above 90%.

Secondly, humidity measurements measure where the concrete ISN'T, NOT measuring the concrete itself. RH measures air space...period.

Thirdly, humidity even in a known volume of air space is a minuscule amount of moisture. NOTE: it takes less than 2 ounces of moisture to produce a 100% RH in a cubic meter of space. To fill that same space with water, it would take more than 264 gallons of water. NOTE: for some quick calculations - a gallon of water weighs 8.34 lbs. It takes 7,000 grains of moisture to produce 1.0 lb of water, which means it would take more than 58,000 grains of moisture to produce a gallon of water. To produce 100% RH in a gallon of air space would take approximately 19 grains of moisture.

How many concrete pores would be needed to produce 1 gallon of air space?

Unless you know exactly how much air space is being measured, you CANNOT calculate the moisture volume!

Water vapor is a gas and is what we consider to be "humidity". As long as moisture remains is a gaseous form, it cannot become alkaline, it cannot create bonding issues and in turn it CANNOT cause a flooring failure.

Perspective

According to the Second Law of thermodynamics, moisture moves/migrates from warm to cool.

In grade level concrete and even with suspended concrete, the surface of the concrete is typically warmer than the underside. Yet we are consistently taught to ignore the laws of thermodynamics because those who SHOULD know have also told us this cooler underside moisture does migrate to the warmer surface.

Unfortunately this isn't much of a surprise since one of the RH Experts I debated awhile back tried to claim that humidity in concrete is different than humidity in the air, and had a few of their supporters jumping in to tell me how stupid I was to believe otherwise...do I need even comment?

Learn to Unlearn so You CAN Learn!

It is an unfortunate reality that misconceptions and non-facts are pervasive and extremely difficult to unseat. As long as there is adherence to non-facts, problems will persist and get worse.

The installers we have worked with, have essentially shed the constant moisture claims they had been enduring for decades.