Document 100361

achieve exquisite masonry, wood or sculptured effects.
The tool that makes the impression is used like a big
cookie cutter on the plastic concrete surface. “Stamped
concrete” is probably the most popular generic name for
the result produced by the tool, although it may also be
called patterned, embossed or imprinted concrete.
A new star is born
Where it’s used
fter two decades of slow, steady growth,
stamped concrete has suddenly become an
overnight success. The idea started simply:
Give customers the rustic beauty of masonry,
plus the durability and low cost of concrete. The applications appeared limitless.
The product’s growth quickened as architects, engineers, developers and contractors alike discovered its
monetary appeal. Customers could save 40 to 70 percent
on realistic brick, tile and cobblestone effects. Contractors could make up to 40 percent and more in profit. A
star was born—as was an entire new market for the concrete contractor.
Private surveys show that the contracting market for
stamped concrete has more than quintupled in size in
the last five years. Five new stamped concrete tool manufacturers have entered the industry in the past two
years. Stamped concrete displays at this year’s World of
Concrete drew unprecedented crowds. The response
rate to recent advertisements in CONCRETE CONSTRUCTION magazine for stamped concrete products
has been in the hundreds and thousands.
New tooling that provides wood and sculpture appearances is now on the market. Other tooling systems
are appearing—and disappearing. Suddenly, after twenty years, the entire construction industry had become
aware of the beauty and benefits of stamped concrete.
One marketing company’s estimate of industry size in
1978 was more than $155 million. Five years ago, the
same company estimated the size of the industry at $25
million. This impressive recent growth has made many
contractors ask important questions about stamped
c o n c re t e. What follows should answer most of these
What it is
First, a definition. Stamped concrete is concrete,
placed, colored and impressed with various patterns to
* Numbers in parentheses refer to metric equivalents listed with this article.
This method of patterning concrete can be used indoors or out, wherever you might use masonry, wood or
sculpture on a horizontal surface (up to a 2:1 grade) .
This means pool-decks and walkways—terraces and
s h ow room floors—kitchens and shopping centers—
highway medians, office floors and much more. The
tools are even being used in tilt-up construction and in
plant-cast wall panels.
The stamped concrete look shows up eve ry w h e re.
Busch Gardens; the Fontainebleau Hotel; Dallas, San
Diego; Singapore; Dublin; Guatemala City—it is being
specified and used all over the world. And it’s not confined to mild climates. The procedure has been used
successfully in De n ve r, Chicago, New York, Vancouver,
Minneapolis and Montana, to name but a few freezethaw areas. There are specifications in use that reduce or
eliminate scaling or spalling.
A wax coating keeps water from penetrating the slab,
reducing the potential for freeze-thaw damage. In addition, the incised lines themselves act as control joints.
Cracking, if it does occur, will generally follow the joint
lines. This means that cracking in a stamped concrete
slab is less noticeable than in a plain slab.
What it costs
One reason for the sudden popularity of stamped
concrete is cost. It is a cost-effective alternative to
p a ve r s, masonry and other similar products. And because it is cast monolithically—one continuous pour—
many of the maintenance problems associated with
those other products are reduced or eliminated.
It is generally 40 to 70 percent less expensive to install
stamped concrete than tile, cobblestone, brick, stone or
sculpture. Of course, price and cost vary from area to
area. The chart breaks down the costs for a 1700-square
foot(1)* job completed in San Diego. By substituting
your costs for those shown in the chart, you can get a realistic estimate of pricing in your own area.
How much stamped concrete can be done in a day depends on the configuration of the slab, the number of
tools to be used, the experience of the crew, weather
conditions and other factors. The general rule of thumb
is that with six tools, three finishers and one or two laborers a minimum of 1000 square feet(2) a day can be
stamped. Depending upon conditions, the same crew
with the same tools can achieve 3000 to 4000 square
feet(3) or more in a single day. But, one note of caution: It
is easy to become confused by “number of square feet
per man-hour” figures because they fail to account for
time spent in placing, finishing and coloring.
How it’s done
Methods vary slightly from one company to another,
but virtually all stamped concrete processes use the
same principles. Most major manufacturers publish
suggested specifications for their processes, which meet
or exceed ASTM materials standards. These specifications are intended to help architects, engineers, developers and contractors specify the exact pattern, color
and effect they want for a job.
First and most important, stamped concrete is concrete. It should be treated as such. Prepare the subgrade
and place your forming, jointing and reinforcing materials (if required) just as you would for conventional conc re t e. Place and finish the concrete as you would normally. Spade, screed, edge and float.
Color the concrete, using dry-shake pigments (or integral color), and float again. At this point, some manufacturers advocate placing 1- to 2-mil(4) p o l ye t h y l e n e
sheeting over the colored concrete surface. This acts as
a finisher when the tools are placed on top because the
plastic is stretched, rounding the edges of the incised
pattern; it also minimizes the possibility of sticking. Other manufacturers prefer a steel troweled (or fresno) finish and recommend placing the tools directly on the
concrete surface.
Because straight lines are important, a chalk line
should be snapped across the surface to be stamped to
square the tools. Once the first tool is squared, the other
tools to be used are lined up and interlocked, and the
stamping process begins. The tools themselves act as a
bridge across the concrete surface upon which the finisher walks.
If the concrete is fresh enough, a man’s weight will
force the blades of the tool into the surface to the proper
depth. As the concrete sets up, an impact tool may be
used to drive the stamping tool into the concrete to keep
the impressions even.
If grouting is required (mortaring the joints such as in
a brick or tile pattern), the incised depth will usually
reach 5⁄8 inch.(5) If no grouting is needed, generally no
more than 1⁄4- to 3⁄8-inch(6) depth should be used. At this
depth, the width of the joint still allows the concrete to
be a good walk surface—even for women with high
heels. If the area will be subjected to traffic, a light broom
finish is generally specified for additional skidproofing.
Before the job is considered finished, many manufacturers specify spraying a wax coating over the surface.
The wax usually contains the same pigment as the surface color. It protects and brightens the finish. After the
other trades have completed construction, another coat
of wax may be applied and buffed to a high gloss, generally nonslippery shine.
What mix to use
Mix design depends upon the strength or durability
required. Normally, stamped concrete is made with a 5to 6-bag(7) mix, using 3⁄8- to 3⁄4-inch(8) nonporous aggregate
and placed at a 3- to 4-inch(9) slump. No matter what size
aggregate is used, the concrete should be tamped (with a
grate tamper) to get the rock down slightly below the
s u rf a c e. Variations for each element in the mix design
may be necessary because of differences in local soil,
climate and job conditions. If necessary, mix designs
can be radically changed. Concrete for stamping may
be placed at high slumps; with 1⁄4-inch (10) aggregate;
with fly ash extenders and with other changes. Such
changes are not necessarily recommended, but can be
made successfully.
Any accelerator or retarder you wish may be used except for calcium chloride. It chemically reacts with color,
causing premature fading. But be careful with retarders
because they tend to set up the entire slab all at one
time. Air entrainment can be used in the mix and is a
must in freeze-thaw areas. But check your color supplier’s specifications first. Air entrainment creates body you
can work with in the finishing steps.
THE JOB: 4-inch-thick unreinforced slab(b)
1700 square feet @ 2.50
SALE PRICE: $4250.00
(a) Labor and material costs per San Diego, California, Labor costs include all union benefits.
(b) Rough grading and forming not included. Final surface hand-finished. Some expansion joint material required.
(c) Integral color. Dry-shake color would require 1100 pounds @ 19 cents. Total, $209.50.
This design is called
random stone.
slab. Third, the wax protects the surface from traffic
wear. And, fourth, the wax keeps the sun from fading the
surface color.
Wax should be applied as often as the area, weather
conditions and other factors dictate. Some slabs, on the
ground more than a decade, look fine without ever having been waxed. Some slabs are waxed every six months.
Generally most slabs are waxed once after finishing and
never again. Rewaxing should be done only if the customer wants to enhance the color.
How to use color
What effects are possible
Most manufacturers, architects and specifiers think
that stamped concrete surfaces look more attractive in
color. It gives the impression an air of authenticity. It’s
like the difference between color and black and white TV.
Some contractors have managed to eliminate color by
specifying special-colored sands in the concrete mix, but
it’s not recommended.
Two basic coloring techniques are being specified by
most manufacturers. A third is in an experimental stage.
Integral color is mineral pigment batched into the mix
either at the ready-mix plant or in the truck mixer on
site. The concrete is poured with the color mixed in. Dryshake color is a mixture of mineral pigment, sand, cement and additives. It is broadcast on the surface of
freshly floated concrete, generally at a rate of 60 pounds
per 100 square feet.(11) This usually produces about a 1⁄4inch(12) topping. Concrete stains are being used experimentally by several stamping tool manufacturers. To
date only one manufacturer is specifying a stain. Stains
alone generally don’t stand up to traffic.
Most concrete stamping tools are versatile. The kind
of impressions you can get depends on your tools, color,
the concrete and your own know-how. For example, you
can create a pillowed or rounded, slump-stone effect (for
cobblestones), flat impressions with rolled edges (for
tiles); or very flat impressions (for brick). You can stamp
step treads and risers. You can use color and wax to create an aged or antiqued appearance. Methods for
achieving these effects vary from manufacturer to manufacturer.
There are four ways to judge the quality of finished
work. First, are the impressions basically the same depth
throughout the slab? Second, are the lines straight?
Third, is the color work even and consistent? Finally, has
the job been done according to specification and customer wishes? The answer to all four of these questions
should be an unqualified yes.
Finished view of
European cobblestone
Each coloring method has advantages and disadvantages. For example, dry-shake color is about one-third
less expensive to use than integral color for a 4-inchthick(13) slab. Howe ve r, it increases the labor factor (although that labor would be tied up on the job in any
event). Dry-shake color gives a harder surface. It also
tends to stand up better in traffic, although some manufacturers report a chipping problem.
Most manufacturers specify a colored wax for a variety
of reasons. First, the pigment in the wax eliminates mottling. Second, the wax keeps water from penetrating the
How to choose a system
Generally, the successful manufacturers (whose contractor customers are also successful) are using a system comprised of stamping tools, hand tools, training,
promotion, color, wax and more.
Stamping tools vary in size from as little as 16 inches
square(14) to as large as 5 feet(15) wide. The materials used
to make the tools range from plastic and fiber glass to
angle iron and cast aluminum. The most popular tools
used in the industry today are cast aluminum. Tool features vary from manufacturer to manufacturer, but virtually all offer some sort of interlocking system that
helps keep the tools on a straight line.
Some tools, particularly small size and plastic ones,
are meant for do-it-yourselfers. They are sold through
building material supply houses. The larger tools are
generally sold by the manufacturer’s captive sales force
or direct from the manufacturer. Some are sold to customers on a franchise or licensing basis. The example
earlier, describing one day’s production, specified six
tools. Howe ve r, many manufacturers sell less than six
tools per pattern. It’s easier to sell the tools that way. It allows a customer to “grow” into the market and build
himself up to production strength.
There are four major considerations when evaluating
• Is the blade of the tool deep enough and large enough
to prevent the underside of the stamp from touching the
concrete surface? If there isn’t enough draft to the blade,
the impressions will always be slightly marred by the underside of the tool, particularly in wet concrete.
• Is the technical backup offered by the firm selling the
tools strong, consistent, reliable and recognized?
• Are hand tools sold with the stamping tools? These are
smaller implements used to finish an impression in
spots larger tools can’t quite reach (such as near the
edge of a wall). Some manufacturers provide hand
tools which form a complete pattern (for example,
a brick). There are arguments pro and con, but it is
generally too easy to misalign with full pattern hand
tools. Hand tools are available with a single blade that
matches the blade of the larger stamp. They may be
somewhat slower to use, but a mistake is likely to be
less noticeable.
• Fi n a l l y, is some form of training or user manual
What to choose—franchise, license or purchase
At this writing, there are two licensing companies and
one franchising company in the industry. Their advantages are simple and strong: They provide exclusive territories, sales support, umbrella advertising and excellent training. Generally, their contractor customers do
outstanding work. The disadvantages of these programs
are nonrecoverable franchise or license fees, a royalty for
work completed, and audits of a company’s books.
These are some of the reasons why manufacturers of
tools that sell them outright have been so successful.
What the future holds
The future of stamped concrete seems to hold unlimited opport u n i t i e s. We can’t see any economic
development short of a depression which would slow
its growth. The only negative possibility is that someone may develop a new product to replace it. But then,
t h e y ’d probably have to wait twenty years for it to
become a star.
Metric equivalents
(1) 160-square-meter
(9) 75- to 100-millimeter
(2) 90 square meters
(10) 30-millimeter
(3) 275 to 375 square meters
(11) 290 kilograms per square meter
(4) 0.025 to 0.05 millimeters
(12) 5-millimeter
(5) 15 millimeters
(13) 100-millimeter-thick
(6) 6- to 9-millimeter
(14) 400 millimeters
(7) 280 to 335 kilograms
per cubic meter
(15) 1.5 meters
(8) 10- to 20-millimeter
Copyright © 1979, The Aberdeen Group
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