Precast Solutions - March/April 2008 - (Page 4)

ABOVE GROUND SMOOTH MOVE THE DEMAND FOR PERFECTLY SMOOTH ARCHITECTURAL SURFACES HAS LED TO THE DEVELOPMENT OF A NEW, DURABLE PATCHING COMPOUND. BY MICHAEL CHUSID, RA, ACI, FCSI PHOTOS BY STEVEN H. MILLER, COURTESY OF CTS CEMENT MFG. A worker at the U.S. Army National Training Center in the Mojave Desert patches a precast Ecolite wall panel. The patching compound was workable in 120 F temperatures and singledigit humidity. O ne of the challenges faced by all manufacturers of architectural concrete is consistent delivery of a finish that is both THE REVOLUTION IN SACKING AND PATCHING Sackers, the workers who patch surface blemishes on concrete, have traditionally had one of the ugliest jobs in the industry. Where aesthetics are critical, concrete is prone to minor surface flaws, including voids and protrusions. For decades, sackers filled bugholes and smoothed rough surfaces using a method that was dirty, messy, unhealthy and only marginally successful in producing a perfectly smooth finish. Their job is known as sacking because they would wet the concrete surface with a cement slurry and then rub it vigorously with a burlap sack loaded with a dry cementand-sand mixture. The dry mix would blow in the wind, covering workers, filling the air with fine particulate matter, and wasting a high proportion of the material. Besides, results produced by traditional sacking were not truly smooth by architectural standards. As concrete became more broadly used as a wall material in highly designed projects, the demand for better finishes beautiful and durable. In this endeavor, precasters enjoy the advantage of controlled factory conditions as compared with those who cast on site. Even so, not every surface turns out perfectly, and surface blemishes and defects sometimes happen. Until recently, a workable, durable repair material compatible with concrete has been difficult to find. Just such a material has been formulated, however. It is a trowel-applied patching compound based on highperformance, rapid-setting cement originally developed to meet the increasingly demanding needs of the tilt-up concrete industry. During the past five years, it has been revolutionizing concrete patching and finishing, and is being embraced by precast manufacturers. Its use in three recent projects, discussed later, highlights its potential for improving the appearance and the bottom line for all suppliers of architectural concrete. 4 PRECAST SOLUTIONS | MARCH/APRIL 2008

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Precast Solutions - March/April 2008 Contents Smooth Move Riding the Waves Comparing RCP With Plastic Pipe Cost-Value Analysis of Storm Sewer Pipe Concrete Testing On a Grand Scale Building Confidence

Precast Solutions - March/April 2008

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