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From brutal to beautiful


Decorative and tilt-up concrete add texture, color, and style to a new range of building types, and Building Teams are putting them to work




Brutalism is the architectural term perhaps most closely associated with concrete. Stark in nature, dull in color, big-box retail and industrial buildings are more apt to come to mind than more elegant structures.

But in their quest to expand the uses for the material in an architectural context, companies are developing new products and contractors are refining existing techniques to make concrete more versatile and aesthetically pleasing.

The use of coloring, stamping, staining, and polishing has grown in popularity throughout the 1990s to today. These techniques are drawing the attention of building owners and have become part of the designer's pallet. In response, contractors are rushing to add these techniques to their portfolio of services.

Along these same lines, use of tilt-up concrete is growing exponentially. Once relegated to mundane warehouse-type buildings, tilt-up has broken out of the box in which it was once held and is now giving contractors the ability to produce distinctive structures.

Stamp of approval

Decorative concrete is the fastest-growing segment of the concrete industry, says James D. Engleman, director of the American Society of Concrete Contractors' (ASCC) Decorative Concrete Council. Engleman, who also owns Engleman Construction, Macungie, Pa., says as recently as the early 1990s, decorative concrete only was about 1% of his company's business.

"Five years ago, we were doing about 15 to 20 decorative concrete jobs per year," says Engleman. "Now, we're doing about 80 to 90 jobs per year, and we have a short season."

Tom Ralston, president of Tom Ralston Concrete, Santa Cruz, Calif., says his company has grown 25% a year in each of the past 10 years doing mostly decorative concrete. He cites a recent study by the American Concrete Institute and ASCC as evidence that the trend in decorative concrete is only just beginning.

According to the study, approximately 3 to 4% of all concrete in the U.S. incorporates color. "By 2007, the number will increase two-fold and possibly more," Ralston says. "I believe the trend will continue to get stronger and more popular."

 
Tilt-up panels at the curved entrance arcade of the Ventana Medical Systems facility, which was completed last January, take on the form of the glass slides manufactured by the company.

"Decorative concrete is no longer a niche market; it's hit mainstream," says Robert P. Harris, director of product training at The Scofield Institute, Douglasville, Ga. "It's the designer's medium of choice."

Responding to demand

The industry, in turn, is responding to the market's need for information and training. Because of its popularity, Portland Cement Association and the Chicago-based Precast/Prestressed Concrete Institute (PCI) are revising their guides on the subject.

With a flood of contractors adding decorative concrete to their list of services, the need for training is all the more important. ASCC conducts training across the country. Last year, materials manufacturers L.M. Scofield Co., Douglasville, Ga., together with MasterBuilders Inc., Cleveland, formed The Scofield Institute, which offers workshops for designers and contractors.

Product manufacturers also are responding by developing new products. "The industry is concentrating on three issues in relation to concrete: appearance, cracking, and making it easier to place," says Michael Gee, marketing manager, North America, for Grace Construction Products, Boston. Surface retarder technology, pigments, and self-consolidating concrete are product improvements that Grace has developed.

Decorative concrete is being used on entryways, floors, walls, columns, and beams in more and more commercial applications, such as entertainment venues, commercial retail, and office buildings. Tenant improvements and schools also are growth markets, says Harris.

Techniques have progressed from coloring and stamping to stenciling, staining, and overlays (see related story, page 53). "Overlays and staining are hot areas," says Harris. Ground-polished decorative concrete also is hot." Grocery store chains are opting for colored overlayments and polishing in lieu of terrazzo flooring.

Tilt-up takes on new look

Tilt-up concrete is accomplished by pouring wall panels directly on the floor slab, then tilting them into place after curing. But tilt-up isn't just concrete boxes anymore. With EIFS [exterior insulation finishing systems], decorative details can be glued onto the walls.

 
Integration of a glass and metal entry softens the look of tilt-up concrete panels at the Lunar Bowl.

Two recently completed commercial projects — the Ventana Medical Systems campus in Tucson, Ariz., and Lunar Bowl bowling center in Blue Springs, Mo. — illustrate the extent to which tilt-up concrete has progressed.

Form follows production

Tilt-up panels mimic the products manufactured at the 182,000-sq.-ft. Ventana Medical Systems campus, providing architectural character to a group of otherwise square industrial boxes.

The tilted concrete panels are 4 ft. taller than the adjacent panels and tilt out every 40-ft.structural bay, says Matthew W. Sears, design principal for HDR's Tucson office. "The result is a wall that steps up and down and in and out without adding area to the building, breaking up the massive look of a large box, and complying with the local building code requirement to break up the wall every 50 ft.," says Sears.

The moon's the limit

With its space-age appeal, the Lunar Bowl, completed in the fall of 2001, may prove to be one giant step for tilt-up contractors in the Kansas City, Mo., area. Two similar bowling centers constructed previous to the project used a pre-engineered metal building frame and roof system with a masonry block exterior. But local contractor Meyer Bros. Building Co., working on an open-book basis, convinced the owner that tilt-up would be less expensive, faster, and a superior product for the project.

The 39,000-sq.-ft. design-build project was constructed using site-cast tilt-up concrete wall panels, in addition to a conventional structural-steel framing system. "Tilt-up is as easy a material to design with as most other materials," says Don Bozich, principal of Bozich Architects, the project's Kansas City, Kan.-based architect. "You just have to think of tilt-up in that context, and consider how you can use it in different ways."

In this instance, Bozich says that the boxy look of the tilt-up was softened by the integration of the glass cube entrance and the lunar concept of interior designer Tom Nicholas, which was carried out onto the exterior panels.

Mainstream methods

Building Teams are only beginning to realize the usefulness of decorative and tilt-up concrete. The more the methods are used, the more new materials, techniques, and equipment will be developed to further mainstream their use.

 

Decorative concrete techniques defined

Four definitions of decorative concrete techniques are offered at www.decorative-concrete.net:

Stamped concretePattern stamping involves "stamping" or "impressing" 3-D patterns into colored concrete with special tools. The product is then sealed, highlighting the colors and providing greater stain and weather resistance. The result is a surface that combines the beauty of masonry with the durability of concrete.

Stenciled concrete A process that utilizes a paper stencil to create a pattern in freshly placed concrete. The stencils are manufactured of heavy-duty paper cut into matrix patterns. It is usually available in rolls of 1,000 sq. ft., in a variety of patterns.

Pre-cut paper stencil is worked into the surface of the wet concrete. Once the surface water has evaporated, two coats of the color hardener are applied and worked into the damp concrete with a trowel.

When the stencil is removed revealing the pattern, residual color chips are removed and the sealer is broom or spray applied.

Stained concreteAn acid stain is not a paint or coating agent; rather, it is a coloring process involving a chemical reaction on a cementitious material. A solution made with water, acid, and inorganic salts reacts with minerals already present in the concrete, resulting color.

Acid stain gives concrete a mottled, variegated, marblelike look. It creates beautiful colors on concrete, mostly earth-tone browns, reddish browns, and greens. Shades can be created by mixing and matching available colors, or applying them at different rates. Acid stain can be applied to walks, entrances, driveways, living rooms, bathrooms, patios, high-traffic areas, and vertically to any cementitious surface. Source: www.acid-stain.com.

OverlaysMade of cement, aggregates, and hybrid resins, polymer cement overlays were introduced into architectural concrete and commercial flooring in the early 1980s. Overlays are used in exterior and interior applications such as concrete resurfacing, stamped overlays, stained overlays, and splatter (pool deck finishes).

World of Concrete pouring into place in Las Vegas

Date: Feb. 4-7, 2003

Location: Las Vegas Convention Center

Exhibitors: 1,700

For more information: www.worldofconcrete.com

By attending four sessions in any one of the following eight seminar tracks, attendees will earn a Master Certificate: concrete basics, residential, decorative flatwork, concrete repair, concrete floors, masonry, concrete production, management, and specialty topics.

Decorative flatwork seminars include: "Using Decorative Overlays on Existing Concrete," "Acid Etch Staining and Sandblast Stencil Techniques," and "Basics of Patterned Stamping," a new addition to this year's program.

Also new is a seminar entitled "How to Avoid Moisture Problems in Concrete Floors and Flooring." Costly coating and covering problems that are caused by moisture emitted from concrete floors will be discussed, with design and construction techniques to help prevent such problems.

Many of the 1,700 exhibiting companies bring product prototypes to the show to obtain user feedback. Mega Demos enable builders to see equipment in action.

Seismic code changes may open new doors for precast

New building codes being adopted across the nation will require designers in areas not typically thought of as high-seismic zones to consider more carefully how their buildings would fare in the event of an earthquake.

“The old design methods made design for seismic forces purely a function of where you were in the U.S.,” says Dale Thomas, manager, marketing and business development for the American Concrete Institute, Farmington Hills, Mich. The new guidelines require designers to into consideration geographic location, soil conditions, and the category of use of the building, says Thomas. “A hospital, for example, has to be designed to a higher standard than a single-story office building,” Thomas explains. “In places like Charlotte, N.C., for instance, a designer might have a combination of soil condition and building use that might require them to design more for a seismic event where they didn’t have to before.”

Irrespective of which of the new uniform building codes vying for adoption around the country is selected, architects and engineers will be faced with tighter parameters for seismic design, says Brian Goodmiller, national marketing director for the Chicago-based Precast/Prestressed Concrete Institute. “Geographic regions in the lowest seismic zones only had to design for wind loads,” he says. “That’s no longer the case.”

PCI is in the midst of conducting workshops nationwide to inform designers seeking options for seismic designs about the potential precast/prestressed concrete offers as a solution to their design challenges. The code changes come at a time when an industry consortium funded by the National Science Foundation and including PCI among other industry organizations is working to implement the results of the 10-year Precast Seismic Structural System (PRESSS) research program. Conducted at the University of San Diego, the program tested the performance characteristics of precast applications in high-seismic areas. A full-size structure was built on the research site to test four frame systems and one shearwall system. All reportedly performed satisfactorily.

The PRESSS program concluded in September 2001. Since then, two projects in California have been constructed using one of the systems, a hybrid moment-resistant frame technology (see BD&C, 08/01, page 32).

“Essentially, precast was not used in high seismic zones because the jointed technology,” says Goodmiller. “Conventional wisdom said this might have been a weakness in the design. This research now reverses this thinking. Through (PRESSS) research program, we’ve demonstrated how precast technology can perform under severe loadings.

“We’re excited,” says Goodmiller. “There’s a thirst for information with the changes in the design codes around the country.” For more information, visit www.pci.org.


  

© 2008, Reed Business Information, a division of Reed Elsevier Inc. All Rights Reserved.




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