CoatingsPro Magazine Supplements

Concrete Dec 2018

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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Page 10 of 43

11 COATINGSPRO CONCRETE COVERED DECEMBER 2018 Concrete Proof F2170, and it provides critical data on the moisture condi- tions that an in situ test alone cannot necessarily provide," Carrigy said. "Reading up to 0.75 inches [1.9 cm] into the slab, the nondestructive moisture content test not only allows for very rapid preliminary moisture mapping of the slab and identification of moisture problems from within the concrete, but it also shows the wettest areas and where best to place the in situ RH probes. By comparing the moisture map with the on-site ambient RH readings and surface temperature, this test allows us to identify moisture issues originating from the surface, such as dew point or condensa- tion issues. ese distinct moisture issues can then be dealt with separately." DeFelsko's PosiTector CMM IS concrete moisture meter probes are another option commonly used to measure RH and temperature in concrete slabs. e reusable smart probes remain powered on and broadcasting via Bluetooth while in situ. If moisture testing indicates a concern, one potential solution is the use of heaters and dehumidifiers to accel- erate the drying process. "Desiccant dehumidifiers are recommended for applications with moisture levels below 45-percent RH," Temp-Air's Slusser said. "Our TD-series of rental desiccant dehumidifiers can get the humidity level in a space down to as low as 15 percent. Meanwhile, PAC-series packaged refrigerant dehumidifiers are ideal for areas with high temperatures and moisture levels above 45 percent. ese control both humidity and temperature levels within a space with a built-in heating mode." On some jobs, even more protection may be needed to ensure full structural integrity. Companies, such as 3M, can supply vapor barriers to protect a building envelope from moisture intrusion, while W. R. Meadows offers its DECR A-SEAL NATUR AL as a low-VOC (volatile organic compound) option. e water-borne sealer is a penetrating water repellent that chemically bonds to the substrate, thus reducing water and salt penetration. "What makes concrete unique, compared to other substrates, is moisture," said Ball of Sherwin-Williams. "When you're coating drywall or structural steel, you could have moisture maybe on the surface. But the fact that concrete is essentially made with water, and that it negatively impacts most coatings that go on top of it, is what makes it unique." "Most epoxy and polyurethane products are subject to some sort of potential issue from moisture coming from the concrete," Ball added. "I think that's what makes it more challenging than other substrates." Repair and Restore Besides moisture issues, many concrete surfaces may also need to have existing defects repaired prior to applying a new coating system. With older concrete, many areas may have spalled, cracked, chipped, or flaked due to years of exposure to the elements, which may happen overhead, such as in tunnels; on vertical surfaces, such as containments or pilings; or on horizontal areas, such as rooftops or secondary containments. "Many factors contribute to making concrete a unique and challenging substrate," said John Fauth, vice president of marketing and business development at concrete coatings, sealers, and repair specialist ChemMasters. "Concrete pH is typically in the 9–12 range, which can be pretty harsh for many coating chemistries. W hen we consider the varied nature of concrete mix designs, environmental conditions at the time of coating installation, moisture content, and demanding service environments, there are a lot of changing dynamics to be considered. And concrete cracks! Cracks can be a problem that results in propagation of the defect through the coating." Fauth cited his company's ColorLastic as an example of an Moisture may also be dealt with using heaters and dehumidifiers. "Desiccant dehumidifiers are recommended for applications with moisture levels below 45-percent RH [relative humidity]," said Temp-Air's Marketing Manager Greg Slusser. For additional protection from moisture, contractors can use vapor barriers and water-repellent sealers, such as W. R. Meadows' DECRA-SEAL that bonds t o t h e c o n c r e t e a n d reduces water and salt penetration. Concrete Proof continued on p. 14

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