Decorative concrete

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Decorative concrete involves utilizing concrete in roles that are not strictly related to its functional elements. Concrete is known for its great strength, especially when combined with steel rebar. Concrete can be used for, among other things, walls, floors and countertops that are structurally sound and also provide a decorative finish that resembles polished stone, with less cost for materials.

Contents 1 Decorative applications on new concrete 1.1 Integral colorants 1.2 Stamping 1.3 Embedding 2 Decorative applications on existing concrete 2.1 Concrete dyes 2.2 Acid staining 2.3 Overlaying 2.3.1 Polymer cement overlays 2.3.1.1 Applications 2.4 Epoxy 2.5 Polishing

[edit] Decorative applications on new concrete

[edit] Integral colorants

Color material is blended with the concrete mix to color the aggregate throughout. Many of the colorants are iron oxides and can create colors including blacks, yellows, and reds. Greens can be achieved using chromium, and ultramarine can be used to create variants of blue. Some of the compounds used to create coloring are heavy metals (including chromium) and can be released during the grinding and polishing of the concrete. These heavy metals can cause severe respiratory problems and environmental damage.

New advancements in integral concrete color do not utilize conventional iron oxide based pigments, virtually eliminating efflouresence and alkali discoloration by using "synthetic primary pigments" SYPP. These synthetic primary pigments are available in liquid emulsion form and are highly concentrated for ease of use and economic savings. SYPP are available in all primary colors. SYPP are also blended with extenders and preservatives to increase the color offering to include most earth tones.

[edit] Stamping

Patterns are impressed into wet concrete slabs or overlays to create textures or to provide the appearance of brick or stone.

[edit] Embedding

Items can be embedded in the concrete for practical purposes (such as brass rails to serve as pot holders on a countertop) or aesthetic ones (such as decorating with shells or fossils).

[edit] Decorative applications on existing concrete

[edit] Concrete dyes

Concrete "dyes" take many different forms and compositions.

Early concrete dyes consisted of generic printing inks that were dissolved in mild solutions of alcohol and applied to concrete surfaces to add a wide array of color to plain gray concrete. When alcohol-based dyes are exposed to sunlight, the color either lightens or fades out completely. Therefore, alcohol-based dyes were more prevalent in interior applications where direct sunlight or other forms of ultraviolet (UV) lighting was not present.

Manufacturers later began dissolving the same printing inks in different carriers, such as acetone, lacquer thinner and other solvents, hoping to achieve increased penetration levels. In addition, UV inhibiting agents were added to new dyes to help with the UV instability issues. However, fading still occurs when the dye is exposed to sunlight.

[edit] Acid staining

Acid staining is not a dyeing or pigment-base coloring systems, but a chemical reaction. A mixture of water, salts and acid is applied to the concrete surface and later neutralized by a basic solution of ammonia and water. This chemical reaction with the existing minerals in the concrete creates new colors on the concrete surface. Due to inconsistencies in the surface of concrete, acid staining creates a variegated or mottled appearance that is unique to each slab. The thickness of this color change ranges from 1/16^th to 1/32^nd of an inch. Exterior concrete surfaces may not color as well as interior surfaces because the environment has leached or percolated out the mineral content.

Chemicals commonly used in acid staining include Hydrochloric acid, Iron chloride and Sodium bicarbonate.

[edit] Overlaying

Concrete overlays date to the 1960s when chemical engineers from some of the larger, well known chemical companies began to experiment with acrylic paint resins as modifiers for cement and sand mixes. The result was a thin cementitious topping material that would adhere to concrete surfaces and provide a newly resurfaced coating to restore the worn surface. Concrete overlays lacked the long term performance characteristics of acrylic resins. Acrylic resins provided good UV resistance, but lacked long term water resistance and adhesion characteristics needed to provide a long term and permanent solution.

[edit] Polymer cement overlays

Polymer cement overlays, consisting of a proprietary blend of Portland cements, various aggregates and proprietary hybrid polymer resins, were introduced over 20 years ago. The purpose of adding a hybrid polymer resin to the cement and aggregate is to greatly increase the performance characteristics and versatility of conventional cements, mortars and concrete materials. Unlike conventional cement and concrete mixes, polymer cement overlays can be applied thinly or thickly without fear of delamination or typical product failure. In addition, polymer cement overlays are much more resistant to damage from salt, petrochemicals, UV, harsh weather conditions and traffic wearing.

Originally intended for use as a thin surface restoration material for concrete substrates, polymer cement overlays were introduced into the architectural concrete and commercial flooring industries in the early 80s. Subsequently, its use in these industries has become standard. Polymer cement overlays are regarded as economical in providing long term, durable renovation without the need for costly and continuous repairs associated with deteriorating concrete surfaces.

[edit] Applications

Polymer cement overlays are used for interior and exterior applications ranging from:

• Skim coat/broom finish concrete resurfacing – Restore and protect damaged, pitted, flaking and stained concrete back to the look of a new concrete surface.
• Concrete regrading & leveling – Repair and level concrete surfaces that have settled.
• Existing substrate redecorating and renovating – Alter the appearance of existing concrete or wood substrates through applying "thin stamped" or "thin stained" overlays, creating new textures, colors and designs. For use on commercial or resident pool deck, this frequently takes the form of "splatter textures" or "knockdowns," in which polymer cement is applied to the existing concrete substrate in a moderately textured finish (average of 1/8” thickness) in various patterns. Often, the texture is knocked down with a trowel to slightly modify the appearance and feel of the finished application.

[edit] Epoxy

Applied over acid stained and/or overlays to seal and protect. Some epoxies are also colored.

The future of the decorative concrete industry and its use of epoxies may lie in the "Fanta Se Floor", invented by Russell Metzger of Albuquerque, New Mexico. The name is derived from an anagram of Santa Fe, New Mexico and with the floor not being what it seems. Mr. Metzger, who owns three (3) patents on the "Fanta Se Floor", found by using a proprietary blending agent with the use of epoxy allowed for an artistic floor with depth, texture and color previously not seen in the decorative concrete industry.

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[edit] Polishing

Concrete is polished with grinders and sanding pads of increasing grit (up to 3000) in multiple stages until it has a hard-glassy finish.