Decorative Floors and Other Flatwork
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What do you get when you cross an artist with a concrete contractor?
It’s no joke; you get great decorative concrete surfaces (floors
and pavements). Through the use of stains, stamps, dyes, colored
pigments, white cement, textured patterns, ornate sawcuts, epoxy
overlay, and more, concrete floors are becoming increasingly attractive
for home and facility owners. As techniques for decorative concrete
finishes are developed, other decorative floor coverings are being
replaced by concrete.
Concrete floors provide an alternative to moisture-sensitive flooring
materials. Using concrete as the exposed finish offers several benefits.
With fast construction schedules, concrete may not have time to
dry adequately prior to placing an adhered finish. If that finish
is impermeable or is applied with moisture-sensitive glue, there
is a potential for failure: debonding, delamination, blistering,
and expansion are a few problems associated with moisture in floors.
More.
For both interior and exterior applications, varying looks are
achieved by employing one or more of these techniques. This page
provides a sampling of some of the available techniques for adding
visual interest to a concrete surface. See the list of available
references at the end for more detailed information about the
processes.
Exposed Aggregate
 One
of the most popular and enduring decorative concrete finishes, exposed
aggregate uses the texture of the rock or stone in the concrete
to embellish the surface. In this technique, concrete is placed
and floated as normal. The concrete is left to set and the surface
paste is later removed by washing and/or brushing. In a variation
of the method, select aggregate is cast over the fresh surface and
embedded prior to setting of the concrete. Washing and brushing
follow as before to remove the mortar from the surface, fully exposing
the natural color and texture of the aggregate. An acid wash may
also be performed to further remove paste from the aggregate and
brighten the surface. More.
Stamping
 Stamping,
which can be used for both interior and exterior concrete surfaces,
has literally made a big impression over the last several decades.
Stamped surfaces are created by supplementing finishing operations
on fresh concrete with patterned or textured mats and templates.
Having started as simple shapes and minimal textures, stamping tools
and techniques have continually evolved to an advanced stage.
Truly realistic textures can be enhanced with color additions, mimicking
natural stone, rock, wood, brick, and more. The only limitation
is the designer’s imagination.
Standard procedures for placing, finishing, and curing concrete
flatwork apply – with a few added steps. Using a stamping
tool or pattern, fresh concrete is imprinted after the initial float
pass and application of a release agent. If color is to be used,
a dry shake color harder may be applied during finishing. The stamping
procedure effectively replaces steel troweling, and the effect is
a unique surface in both pattern and texture.
One way to reduce the cost of materials for
colored flatwork finishes is to place the color only at or near
the surface. There are two common approaches for doing this: Dry-shake
finishes or the two-course method. Both are compatible with stamped
finishing techniques. More.
Integral Colors, Staining, Tinting, and Dying
There are many ways to color concrete—before it has hardened
or afterwards. Integral pigments are mixed into fresh concrete
to create through-body color. Alternately, stains, tints, or dyes
can be applied to hardened surfaces to impart color. Chemical
stains react with hardened concrete to become an integral component
of the floor surface. Pigmented tints or dyes deposit finely ground
pigments into the substrate. To allow for the greatest range of
colors, including pastels and deep, vibrant hues, white portland
cement provides a neutral tinting base for adding color. Alternately,
it enables bright white finishes when used in combination with
white aggregates.
 Logos
and other creative designs made from a combination of stains and
dyes accentuate the lobby of a commercial building.
Stains enhance the inherent irregularities in the concrete surface
with color to resemble a marble appearance.
Stained Concrete
Chemically reactive stains are water-based, acidic solutions
that contain metallic salts. These metallic salts react chemically
with calcium hydroxide compounds (hydrated lime) in hardened concrete.
Such reactions form the insoluble colors that become a permanent
fixture of the hardened concrete surface.
 Partly
due to the irregularity in finishing patterns and partly due to
the inherent variation of the concrete materials, stain chemicals
react in a very irregular pattern – giving it a decorative
effect. As a result, mix constituents and finishing techniques will
greatly influence how effective the staining can be. Controlling
these parameters is important for achieving the best effect from
the stain.
Stains can be applied to old or new concrete; to colored or gray
surfaces; and may be used in conjunction with other decorative
techniques and creative joint patterns. Combining chemical stains
with dyes presents an unlimited palette of colors to create floor
patterns and designs. To protect and enhance the color of the
floor, using a sealer is an important step. However, just as material
selection for the concrete is important, selection of the appropriate
sealer is also important for the performance and durability of
the floor.
Jointing/Joint Patterns
 Sawcut
joints are installed using either an early-entry saw after concrete
finishing or a conventional saw after concrete setting. Alternately,
jointing tools (rather than saws) can add pattern lines to fresh
concrete surfaces. Since joints should be used to control concrete
cracking anyway, this is a simple—and purposeful—method
for adding greater interest to concrete surfaces.
Out of this world! This concrete slab at the Kennedy Space Center
in Melbourne, FL uses creative sawcut joints to enhance the outer
space ambiance in the rocket graveyard. More.
Painting
 Using
stencils and paint, the concrete slab becomes the artist’s
canvas. Some designs are very detailed and intricate and require
etching tools to create fine lines.
Artists at World of Concrete in Las Vegas demonstrate their abilities
of transferring elaborate drawings onto concrete slab surfaces.
Architectural Pervious Concrete
In today’s environmentally conscious climate,
the benefits of pervious concrete to sustainability have reinvigorated
interest in these free-draining pavements. But, although it’s
appealing for its technical benefits, pervious concrete hasn’t
necessarily been attractive…until now. Renewed attention to
pervious pavements has led some people to experiment with improvement
of the surface aesthetics—and spawned a new type of concrete
sometimes referred to as “architectural pervious concrete”
(APC).
Most pervious concrete has a sort of popcorn
look about it: Uniformly sized aggregate, falling within a narrow
aggregate gradation, leads to a concrete with open void areas that
promote fast drainage of large volumes of water. Some like the organic,
rough-textured look of plain pervious concrete. But for those who
want a different look, there are several options for enhancing the
aesthetics. Treatments include color, stamping, jointing, and grinding.
More.
Resources
More information on these and other techniques can be found in
these resources.
Finishing Concrete
with Color and Texture (PA124)
Exploring the
Art of Concrete (CD028)
Bob Harris’
Guide to Stained Concrete Interior Floors (LT283)
Bob Harris’
Guide to Stamped Concrete (LT284)
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