POLISHING CONCRETE A Durability + Design Collection Polishing Concrete A Durability + Design Collection Copyright 2013 by Technology Publishing Company 2100 Wharton Street, Suite 310 Pittsburgh, PA 15203 All Rights Reserved This eBook may not be copied or redistributed without the written permission of the publisher. SPONSORED BY: ii Contents iv. Introduction Getting Up to Speed on Concrete Polishing 1 by Mark Vogel, W.R. Meadows A Real Grind: Concrete Polishing “101” Offers Multiple Rewards 7 by Gary Henry, Durability + Design Concrete Flooring: Polished or Coated? 9 by Gina R. Johnson, Durability + Design Crunching the Numbers on Polished Concrete, Other Flooring Types 16 by Walter Scarborough, HALL Building Information Group, LLC Artistry and Chemistry: Color Theory and Practice with Polished Concrete 23 by Howard Jancy, Jancy & Associates Keeping the Shine: 29 Basic Training in Maintenance of Polished Concrete Floors by Howard Jancy, Jancy & Associates Defining the Undefinable 34 by Brad Burns, Concrete Polishing Association of America SUPERIOR POLISHING PRODUCTS FROM H&C® DECORATIVE CONCRETE H&C CLEAR LIQUID HARDENER & DENSIFIER • Densifies and hardens new and existing concrete • Penetrates and reacts with concrete faster than conventional systems • Minimizes labor costs - is easy to apply, polish & maintain H&C LITHIUM PROTECTIVE FINISH • Protects polished concrete • Increases concrete hardness and improves stain resistance • Provides high gloss reflectivity when burnished ADD COLOR WITH H&C ACETONE DYE STAINS • Available in 16 packaged colors • Colors can be inter-mixed to achieve even more colors • Dry to touch in 20-40 minutes • Perfect for polished concrete or existing substrates A comprehensiveccomprompprrehenehensivvee lineline forr allall your AvailableAAvvailable at youryour local decorativedeccororratiaativvee cconcrconcreteoncrretettee needs.needs. Sherwin-WilliamsSherwin-Williams storstore.e. Scan the code to sign up for our e-newsletter! For more product information, visitvisit wwww.hcconcrete.comww.hcconcrete.com or call 1-1-800-867-8246800-867-8246 iv Introduction This eBook consists of articles from Durability + Design (D+D), durabilityanddesign.com, the Journal of Architectural Coatings (JAC), and Painting and Wallcovering Contractor (PWC) on the subject of polished concrete coatings. More articles on this topic may be found online at durabilityanddesign.com. Cover image courtesy of Brad Burns, CPAA. See the full article on page 33. (Right) Photo courtesy of H&C Decorative Concrete Products 1 By Mark Vogel, W.R. Meadows Editor’s Note: This article appeared in JAC in December 2008. Enhanced performance and appearance attributes have contributed to the increased use of polished concrete in a variety of public and institutional settings. This article reviews the concrete polishing Getting Up To Speed on process, including grinding, surface Concrete Polishing preparation, densifier Grinding, densification systems get sustainability points for buffed-up application and floor performance and appearance attributes polishing. he range of flooring options available in today’s marketplace is vast, with each of these T alternatives offering unique appearance and performance characteristics. As a result, owners and design professionals must evaluate many factors to determine the best flooring option for a structure’s given needs and environment. 2 One flooring system or option currently gain- lows transmission of water vapor and thus is ing in popularity is polished concrete. Al- not subject to failure due to moisture migration though polished concrete is relatively new in from below. North America (approximately 15 years), the When properly installed and maintained, system offers many advantages. polished concrete can last the life of the struc- Concrete is a durable material, and thus ture, avoiding the time and labor of installing meets an important sustainable-design crite- subsequent flooring systems. rion. In addition, the polishing process en- Polished concrete can be used in almost any hances concrete’s natural appeal. These interior area. In exterior settings, however, acid attributes have contributed to the increased use rain has a tendency to prematurely etch the sur- of polished concrete in public and institutional face and cause early deterioration of the shine. buildings such as schools, hospitals, retail Polished concrete can be treated with integral stores, restaurants and other settings. concrete colors, color dyes, and edge-tinting In this discussion, we will seek to provide a products to produce an attractive floor surface. review of the polished-concrete process, which Maintenance is relatively simple and eco- involves a sequence of steps that begins with nomical, and involves cleaning the surface with initial grinding and preparation of the floor. an agent formulated for this purpose. A con- Application of densifying agents and polishing centrated cleaning solution with a neutral pH is with machines employing diamond-grit discs added to the cleaning water in an auto scrub- produce a surface that is durable, attractive, ber. The auto scrubber applies the cleaning so- and highly reflective. A major factor in the in- lution, buffs, and vacuums any remaining Polished concrete can be used tegrity and performance of polished concrete is solution and dirt particles, leaving no residue in almost any interior area, and the use of high-quality liquid hardener and can be treated with integral and a clean surface. Maintenance of polished concrete colors, color dyes, and densifier materials. concrete is quite low in cost, averaging 5 to 7 edge-tinting products to cents per square foot per year. No special produce an attractive floor Polished concrete: An overview waxes or strippers are required. surface. Photos courtesy of Polished concrete, because it does not involve W.R. Meadows Inc. a coating, is a breathable system—one that al- Dry or wet process With dry polished concrete, vacuums are used to extract dust; with wet polished concrete, wet slurry is used to remove concrete parti- cles. The wet-grinding process requires spe- cial disposal methods. With dry polished concrete, pre-separators and vacuum systems are used to control air- borne dust and contaminants. The dry powder or cement particles can be safely disposed of and can even be recycled. Incorporating a low- or zero-VOC (volatile organic compound) hardener/ densifier completes a “green,” en- vironmentally friendly flooring system. A densifier works by chemically converting weak calcium hydroxide [Ca(OH)2] and cal- cium carbonate (CaCo3) compounds in the 3 Attaining the desired level of shine in polished-concrete installations depends on the number of passes of the diamond disc grinder, as each step increasingly flattens the floor and enhances light reflectivity. concrete to form calcium silicate hydrate vided into two categories: Those employing (CSH). CSH is insoluble in water and is highly metal-bonded diamonds (16 to 150 grit) that resistant to water, acids, and other chemicals. are used in the initial grinding or preparation The formation of the CSH is proportionate to phase, and resin-bonded diamond segments increased concrete hardness and density due (100 to 3000 grit) that are used in the subse- to the replacement of soluble lime [CA(OH)2] quent polishing phases. Metal-bonded dia- with CSH. Once the concrete pores are filled monds are more aggressive in their effect on with CSH, migration of moisture from the sur- the concrete substrate than resin-bonded dia- face to the substrate will be inhibited, as the mond segments. process produces a hard, dense, and sealed The initial grinding step removes high spots, surface in which abrasion resistance is in- imperfections, and contaminants such as cure creased by approximately 50%. and seal materials, mastics, or chemicals. This Concrete densifiers are typically based on grinding phase may require one to three lithium silicate, sodium silicate, and potassium stages, but it will consume 60-65% of the total silicate. time required to complete the densification/polishing process. Grinding and The process steps prep work are critical, however, in achieving A true grinding and polishing system requires the ultimate result in the final floor finish. a process consisting of five to 10 steps, de- Resin-bonded diamonds are used following pending on the desired shine of the floor and application of the hardener/densifier to polish its original condition. Assessing the condition and remove the scratch pattern created by the of the concrete requires on-site analysis, gen- initial grinding process. eral knowledge of concrete and mix design, The three primary degrees of shine are cat- and diagnosis of hardness, porosity, and ag- egorized based on the diamond grit of the gregate types. final polishing step: 800, 1500, or 3000— Grinding and polishing techniques are di- which translate to semigloss, gloss, and high- 4 gloss finishes. The cost increases incrementally of the remaining material from the surface, de- by 10–15% when upgrading from a semigloss pending on heat and airflow conditions. Spe- to a gloss range, and another 8–12% when cific manufacturer directions should be upgrading from a gloss to high-gloss range, referenced, as some application methods vary. based on the total value of the project. The ma- It is critical to not allow the densifier to dry jority of the cost is related to the preliminary on the surface, as this may leave a white preparation stages, as labor intensity is great- residue