Decorative Concrete Institute

Bob Harris

Consulting • Education • Installation • Training

 

Scoring and staining transformed this concrete floor into a work of art.

The words beautiful and concrete are rarely used in the same sentence, yet decorative concrete techniques can transform a drab driveway patio or walkway into a beautiful surface that adds drama to a home's appearance. Whether a homeowner wants the look of brick, slate, pavers, river rock or cobbles, concrete can be utilized to create a life-like illusion.

"Concrete is a very versatile material. It's totally malleable like liquid rock," says Bob Nussmeier general manager of sales and marketing for L.M. Scofield, a manufacturer of products used in decorative concrete application.

With the techniques available today, it's difficult, if not impossible, to distinguish decorative concrete from the real thing, says Frank Piccolo, founder of ArtCrete and director of the Decorative Concrete Council. "People will swear it's real brick or stone."

The development of advanced colorants and texturing processes make these stunning deceptions possible. The decorative concrete industry is growing, says Piccolo, who first experimented with decorative concrete materials in his own backyard and has since transformed ArtCrete into an international company. "I think we're seeing the beginning of a real trend," he says.

Bomanite developed decorative concrete techniques in the 1950s, but they didn't catch on in a big way until recently. Even in the mid-80's, when Piccolo entered the market, there were few companies in the field.

"Back then you'd go to a trade show and there would be three or four exhibitors," he says. "Now there may be 50 of them."

There are several reasons for this growth. The Internet has had a major impact, Piccolo believes, because homeowners can find information on the subject easily. The construction industry and consumer publications arc also starting to sit up and take notice, he says.

Price, durability and versatility are all factors that are fueling this growth, says Nussmeier. Decorative concrete can be used on both exteriors and interiors. In fact, he says, it's particularly attractive to families who enjoy an indoor/outdoor lifestyle, because a look can he carried from the home's interior to its exterior.

There are six major techniques used to achieve these intriguing counterfeits that are often mistaken for the work of a fine craftsman. They are stamping, stenciling, overlays, spray overlays (micro-topping), staining and scoring, and wall form liners.

Stamped Concrete

Pattern-stamping is a well-established, economical and popular technique. After a concrete surface is poured and floated, a color hardener--a tinted, powdery sub-stance which is a blend of mineral-based pigments, portland cement, silica and quartz--is applied and worked into the surface using a trowel.

The patterned impressions are made by placing a flexible, reusable stamping mat on the before it has fully dried. The mat is pressed into the concrete surface by stepping on it and moved from spot to spot until the entire surface is imprinted. Many looks are achieved with stamping, including brickwork, stone and tile. The stamping mats are often made from molds cast from real paving work.

After the concrete cures, it is rinsed to remove loose color hardener. It is then sealed, often with a UV resistant sealer that prevents color changes or fading caused by the sun. There is no color differentiation in the "grout" and "bricks" or "Stones" when using this method.

Stenciled Concrete

Stenciled Concrete is a technique for new concrete surfaces. After the concrete is poured and floated, overlapping paper stencils bearing the desired pattern are laid across the smooth, wet surface. The stencil lays flat against the surface. A float tool is passed over the surface and embeds the stencil into the concrete.

A color hardener is spread over the surface. The color hardener bonds to the concrete, says Nussmeier and becomes the base color. Next, accent colors are applied in the same manner. Together, these color toppings characterize the look of the "brick" or "stone". The underlying concrete slab provides the color for the contrasting "grout."

Once the concrete has dried to a weight-bearing point, the stencils are pulled up, revealing the pattern. Removing the stencils creates small pieces of debris, which are removed with a leaf blower. The surface is covered with a resin-based sealer for protection.




Sprayed-On Overlays (Micro-Topping)


Overlays are used to turn existing plain concrete flatwork into decorative surfaces. After cleaning the surface of grease and dirt as well as repairing any cracks in the Concrete, a colored concrete-resin mixture is applied to the surface in a very thin layer. This mixture, which bonds to the underlying concrete, will show up as the "grout" between the "bricks" or "stones".

"This (concrete-resin layer) is very good to use if the surface isn't perfect because it creates a smooth surface," says Nussmeier. "The mixture is also self-leveling."

When the clean, new surface dries enough so that it can bear the weight of a person, the decorative techniques are applied, says Piccolo. Both stencils and stamping mats can be used on the concrete-resin surface. If stenciling is the preferred technique, the stencil is laid out on the surface and color hardener is applied with a hopper gun, such as the kind used to apply drywall texture. Additional accent colors can be applied to the surface which can be finished with a texture roller that creates dimples and ridges so that is looks more natural, says Nussmeier.

Stamping can be accomplished with as little as a one-fourth inch depth of concrete-resin. The final step is to seal the new surface with a resin-based sealant.

Staining/Scoring/Etching

Staining provides a more artistic look. Stains can be applied to new and existing concrete, as well as overlays. Stains are often used to create geometric patterns, antiquing and wood graining on surfaces.

Concrete stain, a combination of water, hydrochloric acid and mineral salts, reacts with the lime within the concrete. This reaction changes the color of the surface permanently. Because different areas of the surface respond differently to the stain, an uneven, marble-like look, often described as a patina, results. “This creates a wonderful mottled look,” says Barbara Sargent of Kemiko Concrete
Floor and Stain.

The Kemiko stain, available in six colors, is applied with an inexpensive handheld pump-up garden sprayer. "The coverage is awesome " says Sargent. "It will cover 400 square feet – about the size of a two car garage – per gallon. And that includes two coats of stain, so it is very economical."

After staining the floor it can either be sealed or waxed. A sealer darkens the floor dramatically, giving it a high gloss wet look, while a wax provides a soft, satin sheen and allows the mottling to show.
Scoring and etching are often used in conjunction with staining. Scoring is the sawing of fine lines into the concrete surface with a diamond blade. Etching is done with stencils and a sandblaster. Both techniques are used to define areas that are then stained. Scoring is generally used to create both large and small fields of color and designs. Etching is used to create borders and other decorative details.
These techniques can be used in both interior,,-, and exteriors. Sealing these surfaces is very - important, says Nussmeier.

Wall Form Liners

Wall form liners are used to create vertical, rather than horizontal, decorative concrete surfaces. The forms, which mimic stone and brick walls, are set up and the concrete mixture is poured between them and allowed to dry. They can be textured and stained to look like the real thing.

Homeowners can also install their own decorative concrete using a new do-ityourself kit from Artcrete. The U-Coat-It kit, which reached store shelves in May, contains all the materials necessary for completing an overlay project.


 

 

   
 

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