CoatingsPro Magazine - January 2022
Bubbling Marijuana Facility Floor
Valerie Sherbondy And Lou Frank 2021-12-29 13:15:53
When any facility is being converted for a new use, problems with renovating or upgrading the concrete floor can deliver a surprise if the building’s previous history isn’t fully known. The resulting failure in the floor coating system is infuriating for both the applicator and the owner, and — as in this case — they might not have a clue as to why it happened in the first place.
The lesson: It’s critical to learn as much as you can about the floor and its former uses before you begin applying coatings. This was a floor coating lesson learned the hard way. Fortunately, it has a good ending.
This lesson was learned by a major national contractor and the coatings subcontractor tasked with converting a former industrial building into a marijuana-growing facility. When bubbles appeared in the newly coated floor, the coating manufacturer was called onto the project. Through some proactive investigation and old-fashioned customer service, the problem was identified and the issue resolved.
It was later determined that the building was used as a machine shop, which likely resulted in oil spills and contamination in the concrete.
The Job
The facility in question was a 50,000-square-foot (4,645.2 m2) building that stands on a hillside in an industrial park in the Mid-Atlantic region of the United States. Beyond knowing that the floor had a former life, which was described by the commercial real estate broker as “light manufacturing,” the stakeholders of this project knew little about the building’s previous uses.
It was later determined that the building was used as a machine shop, which likely resulted in oil spills and contamination in the concrete. That information would prove critical in determining the cause of, and solution to, the bubbles in the concrete floor coating.
The owner hired a major national general contractor (GC) to lead the renovation and build-out of the facility, converting it to serve the growing demand for CBD (cannabidiol) products, which have recently been legalized in many states. The contractor retained a highly experienced coatings subcontractor to provide a resinous coating system to the concrete floor. The system chosen was confirmed with the coating manufacturer with the purpose that it would deliver years of service in the renovated facility.
Uncharacteristically, the surface preparation had been completed by the general contractor before the coating application crew arrived on site. This coatings subcontractor typically does his own surface prep work, as it allows the subcontractor to be sure it was done correctly as well as learning as much as possible about the condition of the floor prior to coating application.
For this subcontractor, not completing his own surface prep work was a concern, but he weighed his options of arguing with his client and determined that the size of the job outweighed the potential risks.
The general contractor informed the coatings professionals that the floor had been tested for moisture and the moisture vapor emission rate (MVER) was 10 pounds (4.5 kg) per 1,000 square feet (93.0 m2) per 24 hours. That’s well above the 3-pound (1.4 kg) limit for typical coatings as suggested in ASTM F710 “Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring.”
Based on that information, the subcontractor used a moisture mitigating primer followed by an epoxy mid-coat. This system was designed to handle the light-to-moderate foot and wheeled traffic that was expected on this industrial facility floor. Both the primer and epoxy coating were applied with no issues, but that didn’t stop the trouble.
The liquid that oozed from beneath through the bubbles of the resinous floor coating was brown with telltale rainbow colors of oil on top of water.
The Problem
Lurking beneath the coating was an unforeseen problem for everyone.
About four weeks after the job was completed, bubbles began to appear in the floor. They showed up in isolated areas and not across the entire floor. Called in to inspect the issue, the flooring subcontractor found that some of the bubbles were leaking brown liquid that appeared to be pushing up through the coating. The liquid that oozed from beneath through the bubbles of the resinous floor coating was brown with telltale rainbow colors of oil on top of water. The owner and general contractor assumed that the messy liquid was somehow caused by the coatings. The blame was placed on the subcontractor for selecting an incorrect coating or not applying it properly. Needing to avoid a very expensive re-grind and re-coat, the subcontractor teamed up with the coating manufacturer to prove this was not the case.
Clearly, the floor had more problems than just increased MVER, and the combination of the moisture and likely contaminants meant this job was going to be difficult — and expensive — to deal with.
The discovery of the floor’s problems sent tensions high. The building owner had the GC under a tight completion deadline to get the building operational, and they placed blame on the coatings subcontractor, even implicating that the coating might also be at fault.
In addition to the visual observations made by the subcontractor, the coatings manufacturer sent a representative to the job to take photos and samples of both the applied and cured coatings and the brown ooze. The samples were sent to an independent forensic coatings lab where they were analyzed.
The laboratory investigation consisted of a visual and detailed microscopic examination and infrared spectroscopic analysis. First, chips of the coating were examined under a microscope. The topcoat was white and glossy with a textured finish. The bottom surface was gray and uneven with areas of adherent cement residue. Some chips had a deposit of yellow discoloration on top of the surface. When viewed under magnification, the residue did not have a crystalline appearance. A sample of the residue collected from the floor was examined separately and found to have a yellow/ orange color, and it did not have crystalline characteristics.
An infrared spectroscopy analysis was then conducted on the discolored region of the coating chips, on the residue collected from the floor, as well as on the amine hardener components of both the primer and epoxy because they had an amber color similar to the discoloration and floor residue. The spectroscopic analysis of the discolored areas indicated carbon-hydrogen materials similar to a wax or oil-based material, calcium carbonate, silicates, possibly phosphate drying agents, and bound water.
The analysis determined that the bound water, calcium carbonate, and silicate materials were most likely the result of contact with an older concrete floor. The wax or oil and possible drying material were likely contaminants from when the building was used as a machine shop. This analysis also ruled out that the contaminants were caused by a component of the coating materials. No amine from either coating was identified as part of the residue by this analysis.
Separately, the company that the facility owner contracted for testing also yielded findings concurrent with those of the independent lab.
The Results
Based on the agreeing results of the tests, the building owner, eager to get the marijuana-growing facility up and running, realized he could not blame the contractor or the coating for the problems with the floor. Further, the owner saw that the contractor was serious about fixing the actual problem rather than assigning blame. The owner asked the coatings subcontractor to fix the bubbling floor — redoing the entire floor and not just the bubbling sections — and paid him for the additional work.
The coatings manufacturer’s tech team worked closely with the general contractor and coatings subcontractor, specifying a completely different coating system designed for such challenged floors: a surface-tolerant polyamide epoxy primer with a polyamide-cured novolac epoxy topcoat. The products in the second system are designed to work with moisture-laden and moderately contaminated substrates. It’s now been several years since the repairs were completed, and there have been no further problems with the floor coating. The facility owners are happy, and their customers are likely happy, too.
The Lessons Learned
The main lesson that both the building owner and contractors learned together — and that every stakeholder should consider — is that it is important to know what you are over-coating. You can learn what the condition of the substrate is, so, whenever possible, do your own surface preparation.
The subcontractor on this project is a veteran of the concrete floor coating industry, and he normally follows that best practice. This time, though, he didn’t. That prevented him from inspecting the slab prior to preparation, which may have shown visible oil stains or wax discolorations from decades of machine shop use.
Even if you’re unable to do your own prep, you can do a quick test to verify that surface contaminants have been removed: Put a drop of acid on the concrete. The acid should quickly react with the alkaline concrete and bubble. If you don’t see any bubbling, something may be blocking the acid from reacting with the concrete.
Another factor in this premature coating failure was that the building is located on a hillside. That probably meant that rainwater had run along and underneath the building for decades prior to the latest coating installation, which is likely the source for the increased MVER.
Much was learned by all involved with this flooring project, and hopefully, now that the stakeholders are all aware of why and how this premature coating failure occurred, they can ensure that this type of problem will occur for them never again.
The main lesson that both the building owner and contractors learned together — and that every stakeholder should consider — is that it is important to know what you are over-coating.
VALERIE SHERBONDY is the technical manager of the Analytical Laboratory for KTA-Tator, Inc., an independent consulting and engineering firm specializing in inspection, consulting, and laboratory services for the protective coatings industry. Sherbondy has worked for more than 25 years in the paint industry. She has been involved with hundreds of paint and coating failure investigations and has analyzed or tested hundreds of different coating materials, from architectural to industrial coatings. For more information, contact: Valerie Sherbondy, vsherbondy@kta.com.
LOU FRANK is the business development director at Coatings for Industry, a 50-year-old formulator of performance coatings. He is most widely known as the founder of CoatingsPro Magazine, now owned by AMPP. He has a business degree from the University of Maryland. He has served as the publisher of online platforms and as a board member for several industry organizations. For more information, contact: lou.frank@cficoatings.com.
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