Poring Over Flowable Cement Terrazzo - International Masonry ...

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Desired service rating of the floor also factors in when choosing a primer. 3 As with the moisture and crack suppression membranes, the primer should be sourced from the same manufacturer to ensure compatibility with the binder. Pouring the matrix Flowable cement products differ from other types of terrazzo due to the composition of their matrix, along with the resulting viscosity and impact on the sequence of installation steps. Traditional systems, such as sand cushion or epoxy terrazzo, require most of the aggregate be added to the matrix during the initial mixing. This results in a relatively stiff mixture that gets troweled into place between the divider strips. The mixture hardens in 24 to 48 hours, and is subsequently ground to the desired finish. It has a calculated volatile organic compound (VOC) measurement of 0 g/L, since the materials are all inert. (This means, unlike most other terrazzo assemblies, flowable cement products are entirely VOC-free.) Flowable terrazzo’s binder comes bagged as a powder and is mixed with water and poured in place before any aggregate is On a typical terrazzo floor, trained installers trowel on the matrix/aggregate mixture. added. The proportions of 4.50 to 4.73 L (4.75 to 5 quarts) of water per 22.7-kg (50-lb) bag of powder must be followed precisely and consistently, taking care not to over-water the mix. Typically, two bags are mixed at a time, using an eggbeater paddle at 1100 rpm. Over-mixing could trap air, which may shorten the product’s pot life or cause pinholing during application (or floor-curling thereafter). When properly mixed, this binder is the key to flowable terrazzo. APA.indd 1 10/5/07 2:59:02 PM December 2007 The Construction Specifier 37 CS-Dec07-a.indd 37 11/13/07 2:30:18 PM
On a flowable cement terrazzo floor, the binder is mixed and poured before the aggregate is applied. In lieu of pouring, flowable cement matrix may be pumped onto the floor, as it is partially loaded with aggregate. This can save considerable time when pouring large areas of floor. The in System 1. Insulation 2. Air Barrier 3. Vapor Retarder In a single application, Demilec’s unique Heatlok Soy spray foam insulation creates a high-performance building envelope that offers long-term thermal resistance, an excellent air barrier, and a recognized vapor retarder in a wide variety of commercial and residential buildings. This highly-efficient, closed-cell, rigid polyurethane foam can only be applied by authorized contractors, trained and certified by Demilec USA as part of its ongoing commitment to environmental protection. 1-877-336-4532 • Fax: (817) 633-2000 E-mail: info@heatloksoy.com • www.heatloksoy.com Wearing spiked shoes, an International Masonry Institute (IMI)-certified installer broadcasts aggregate by hand. Further, flowable cement terrazzo can be ergonomically preferable for those in the trades, as it can be poured or pumped from a standing position rather than troweled from the kneeling one dictated by traditional terrazzo. The matrix is spread as it is poured. Using a gage rake typically calibrated for 6.4 mm (0.25 in.) in height, the terrazzo mechanic pushes and pulls the material to the outer limits of the pour, ensuring consistent elevation. The installers pouring and raking the material wear special spiked shoes enabling them to walk in the area of the pour without interfering with the binder’s flow. Flowable cement terrazzo binder comes in eight standard neutral colors, with custom hues available. However, most of the floor’s color comes from the chips. While resinous epoxy offers many more color choices for the binder, the vast selection of aggregates is virtually the same between the two systems. Broadcasting the aggregate Broadcasting the aggregate is one of the most important terrazzo installation skills required. Flowable cement terrazzo accepts nearly any Size 1 or 2 aggregate, including recycled glass. The sizes of the chips are gauged per industry standards. For example, Size 1 chips pass through a 6.4-mm (0.25-in.) screen and are retained on a 3.2-mm (1/8-in.) screen; Size 2 chips pass through a 9.5-mm (3/8-in.) screen and are retained on a 6.4-mm screen. Any type of marble or calcareous stone may be used as chips. In a departure from traditional cementitious terrazzo, even coated and/or recycled glass are permissible. Demilec.indd 1 6/6/07 4:13:12 PM 38 The Construction Specifier December 2007 CS-Dec07-a.indd 38 11/13/07 2:30:19 PM
Page 1 and 2: Poring Over Flowable Cement Terrazz
Page 3 and 4: Photos courtesy International Mason
Page 5: Photo courtesy ProTile and MAPEI Al
Page 9 and 10: The floor is ground in stages, usin
Page 11: Notes 1 This article is adapted fro

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