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.
Issue link: http://coatingspromag.epubxp.com/i/101883
Shot Blasting Pros Cons Will remove existing thin coatings with Shot blasting must be used in conjuncease tion with an adequate dust collection system Can remove eroded concrete to expose Equipment is expensive, especially a suitable layer for adhesion multiple machines Multiple machines can be used to Some machines may have problems prepare a large area in a short amount removing flexible coatings, some highbuild coatings, and resurfacers of time Profile depth can be adjusted Inconsistent deeper or lighter profiles may be cut if speed is not maintained or if used over "soft concrete" No water needed to clean surface, so the Deeper profiles necessitate the use of concrete is ready to coat immediately extra resurfacer to cover profile marks Variety of widths available Noise may be a problem CSP-3 through 7 achieved ing coating and a significant layer of the existing concrete, while creating a profile in the concrete. This method is especially useful in floor spaces that work with animal fats or oils, which will absorb easily into concrete greater than 1/8-inch (0.317 cm) deep. Other instances include preparing a steel shake floor for receiving a new electrostatic dissipative system. Simply grinding over these contaminated floors may address the surface imperfections but will not penetrate deep into the concrete to expose a fresh layer like shot blasting can. Shot blasting takes full advantage of the porous nature of concrete by providing a highly favorable adhesion environment for a primer and urethane or epoxy resurfacer. First, concrete's porous matrix is exposed in freshly shot-blasted concrete, which increases the penetration of lower viscosity coatings, creating a mechanical bond that anchors the coating in place. Second, a profiled shot-blasted surface increases the overall surface area, which means far more contact points for the coating to spread over. More contact points means better adhesion. scarifying: even more Contact Points = Better Adhesion Like shot blasting, scarifiers are versatile machines that make short work of all kinds of existing coatings by utilizing a rotating drum with tungsten or hardened steel cutters (varying in shape), which continually strike the concrete, leaving a clean, roughened, or textured surface. The pros and cons are similar to that of shot blasting with some added benefits. Li ke shot bla st i ng , t he newly scarified surface will not only expose concrete's porous surface but also yield a Scarifying Pros Cons higher surface area of peaks and valleys to create an adequate mechanical bond for a resurfacer. Conclusion These preparation methods are not the only methods available to a flooring contractor; other processes include scrapers and scabblers, for example, which perform the same function as grinders and scarifiers. One scrapes the surface; the other pecks at the concrete, leaving deep profiles. Regardless of which concrete surface preparation method is chosen, not preparing the surface increases the chances of future adhesion failure. Communication between the flooring product specifier and the contractor is crucial to avoid performing a preparation method that adheres to the letter of the specification but is actually inappropriate for a particular flooring application. A floor coating, blended in accordance with its instructions, does not know whether the concrete was adequately prepared ahead of time. Picking the wrong method of preparation now will likely create aesthetic issues or dramatic product failure in the future. CP References 1. A Berger, W., "Surface Preparation for Concrete Flooring", J. Prot. Coatings & Linings, 1989. (Web). 2. See also Tim Edward's article "How to Prepare and Paint a Concrete Floor" (Sept 2008), visit http://www.articlesbase.com/home-improvement-articles/ how-to-prepare-and-paint-a-concretefloor-545620.html. Jason sMith is the senior research and devel- Will remove existing coatings and resur- Scarifying must be used in conjunction facers with ease with an adequate dust collection system opment chemist for The Garland Company, Inc., Can remove eroded concrete to expose Equipment is expensive, especially a suitable layer for adhesion multiple machines mance solutions for the commercial building Cutters can be switched out to address Medium to high risk of surface damage different preparation needs a senior development chemist for an interna- Depending on the machine size and Inexperience may lead to inconsistent horsepower, 350 to 1600 sf/h can be profile tracks prepared CSP-6 through 9 achieved 38 CoatingsPro g January 2013 a Cleveland-based manufacturer of high-perforenvelope. Prior to joining Garland, Smith was tional manufacturer and distributor specializing in polyurethane adhesives for the industrial and consumer markets. He has an M.S. in polymer chemistry and coatings technology from DePaul University, Chicago. Smith can be contacted via e-mail at jasonsmith@garlandind.com.