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COATINGSPRO SEPTEMBER 2016 41 Science Behind It Creating a Comprehensive Antimicrobial Concrete Coating System By Sean M. Walsh, Marketing and Product Development Manager for Protective Industrial Polymers A ntimicrobial polymer concrete floor and wall coatings have been around for some years now. Most coating manufacturers offer some type of "antimicrobial " coating. In most cases, this coating is "field manufactured," meaning there's a type of antimicrobial additive in the resin base, which is activated with a curing compound and applied directly to the substrate. At the Niabi Zoo project, the crew from Concare used Protective Industrial Polymers' Protect AM-PT-BW to the walls and Protect AM-PT to the floors for antimicro- bial protection. Debunking the Myth A lthough coatings can contain an additive with antimicrobial properties, this does not mean that the coating itself will be resistant to dangerous microbes, including bacteria, molds, mildew, fungus, and spores. A coating can be categorized as an antimicrobial coating by the mere fact that it contains a known antimicrobial agent. e reality and not well known fact is that this alone does not mean the final coating is antimicrobial. erefore, step one in creating a comprehen- sive antimicrobial system is to fix what's been inherently broken all along. Different antimicrobial additives, at differing concen- trations, react differently in various types of polymer technologies. W hile one antimicrobial additive might work in an epoxy coating, that additive may not react the same way in a polyurethane coating, for example. To ensure that the proper qualities can be offered to clients such as the Niabi Zoo, it is important that proper bench testing be done when formulating coatings that are intended to inhibit the growth of dangerous microbes, such as per the American Association of Textile Chemists and Colorists (A ATCC) and International Organization for Standardization (ISO) testing standards. ese tests involve closely monitoring antimicrobial additive percentages within the chosen polymer matrix and creating cured specimens. ese coating specimens must then be independently tested to ensure the cured coating does not support the growth of the specific microbe(s) of concern. What Lies Beneath W hy is this necessary? Concrete, by its very nature, is a porous material that retains and transmits moisture. Concrete substrates are full of dark, damp crevices and capil- laries that make them ideal breeding grounds for a number of microbes, including bacteria and fungi. Even w ith the best coating technologies, installed w ith the most professional methods, coating wear and joint failure can occur. Additionally, normal or ag gressive wear from foot and equipment traffic, abrasion loads, hot water wash dow ns, and abrasive chemical cleaning can cause f loor or wall surface damage. Wear, chips, spalls, and cracks in f loors and walls are a perfect breeding ground for danger- ous microbes. A nd because common cleaning /wash dow n techniques cannot penetrate deep into these areas, bacte- ria can live for extended periods in the concrete and pose potential health threats. is is certainly a concern in areas subject to thermal- shock or cycling generated from hot and cold temperatures and wash downs, such animal care and wash areas. erefore, it is important to protect the most sensitive part of the floor or wall system, which is the substrate itself, and also to fill all control and expansion joints with an antimicrobial flexible sealant in addition to the coating. Most concrete densification products are designed to react at the substrate surface level. is aids in producing a harder, easier to polish concrete substrate. Protective Industrial Polymers' Protect AM-PT products don't react as quickly and, therefore, are able to penetrate further down into the concrete substrate, hydrostatically sealing the concrete substrate from within. is means that Protect AM-PT fills the voids and capillaries up to 6 inches (15.2 cm) within the concrete with an aqueous gel, which contains antimicrobial properties, sealing the matrix of the concrete and limiting its permeability, in effect making the concrete substrate and not just the surface "antimicrobial." Putting It All Together e key to achieving comprehensive antimicrobial protection is to prevent the growth of microorganisms throughout the client's floor or wall system and deep within the concrete substrate. e whole idea here is a redundant, layered means of antimicrobial protection. An antimicrobial substrate that is coated with an antimicrobial primer and subsequent antimicrobial build coats/mortars and topcoats provides the most comprehensive method for preventing microbe growth. As expected, proper maintenance, repair, cleaning, and resealing the topcoat are recommended, but Concare's ultimate goal was to create a surface that will not support the growth of dangerous microbes, even as the coating wears or cracks over time. CP