CONCRETE FINISHES

Decorative Stamp Concrete

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Northwest company making its mark on concrete.

One of the most popular ways to adding a natural look to new concrete is stamp concrete.  You can imagine after pouring with gray concrete for so long, we asked ourselves if there was any way to add pizzazz to our jobs.  The answer came in various patterns and colors which was a sure hit with the public:  stamp concrete.  

Twenty years later, the research and hard work was well worth the time.  ACDI offers a large variety of stamp designs and colors to fit every possible design.  We are certified installers of two different stamp systems which allows clients to choose combinations that enhance the value of their home or business.  In addition to a variety of colors and patterns,  stamp concrete can also be combined with standard concrete finishes.  

How's It Work?  

A common question ACDI is asked is "What's the process with stamp concrete ?" There are many keys in making a successful stamp pour go right and ACDI takes note of all details when it comes to the design of a project.  As many of us know, living in the Pacific Northwest comes with many weather-specific challenges.  Our damp climate affects the timing and preparation of all concrete projects.  

Sub grade preparation and strength of sub grade (ground) will determine the longevity, strength, and potential for cracking.  One thing is guaranteed with concrete--it's going to crack.  In order to reduce the risk of cracking, ACDI takes quality time to level off the ground and compact the sub grade.  If the ground is too soft, then additional fill materials (such as crushed gravel) can be imported and compacted tightly.  

After the sub grade is prepared, we can begin forming the project in your design and install rebar to hold the slab together.  Next, it's time to pour, place and finish the slab.  Depending upon your access, some concrete projects require line or boom concrete pumps in order to transfer the concrete from the truck and into the forms.  Driveways usually do not require concrete pumps, however, if the driveway is steep then you'll need a concrete pump.  Patios, pool decks and walkways in backyards (or tight locations) require concrete pumps in most cases. Once we have the excess concrete leveled and sloped properly, we begin throwing color hardener (base color) onto the gray concrete and troweling the pigment into the surface.  You can substitute broadcasting (throwing colored pigment) onto the surface by ordering colored concrete from your local supplier (See Colored Concrete).    

The color hardener (base color) is covered with a colored release agent usually seen in the low areas of a stamp pattern.  Release comes in a variety of colors and allows ACDI's decorative division to place the stamps on top of the slab and imprint the pattern without sticking to the surface.  The entire slab is covered with release powder when the finishers have completed stamping.  You won't be able to see the base color of the slab until a majority of the release power is removed.  Once the release is washed off, the concrete is allowed to dry and sealed.  

Applications

The most common stamp concrete applications are exterior hardscapes:  driveways, patios, walkways, steps, pool decks and interior concrete floors.  However, ACDI does install custom stamp concrete on engineered and reinforced decks, countertops, and retaining walls.  

If your considering stamp concrete for a driveway, there are some characteristics you need to know about.  Consider the dramatic visual effect of stamping the entire driveway - some consumers enjoy the simplicity of one pattern because multiple stamp patterns can become too busy and take away from the house.  In other cases, adding 12" - 16" stamp borders and installing cheaper basic gray concrete inside the borders adds appraisal value while not breaking the bank.  Most stamp concrete requires acrylic sealer which resists moss and dirt from staining lighter colored concrete.  Sealers are also beneficial because they accept most of the traffic wear vs. the concrete surface itself.  However, when you apply any concrete sealer they also resist water seeping into the pour of the concrete leaving puddles when it rains which sometimes isn't preferred in a driveway.  Unlike exposed aggregate, sealed stamp concrete has shallow high-and-low-spots like real stone which can puddle during rainy weather.  Most concrete sealers last approximately 2-3 years depending upon your traffic and require a re-sealing process.  Some people consider this a turnoff and would prefer less maintenance.  However, a majority of ACDI customers find re-sealing very easy which only require the sealer materials, a painters roller and a pan.  So, the tradeoff for concrete sealers is maintenance, protection, enhanced concrete colors and a impervious surface.

For people looking to avoid the sealing process ACDI recommends sandblasting stamp concrete which requires no annual maintenance once complete.  

When deciding on stamp patterns for patios, consider how your patio furniture will sit on top of the surface.  No one wants to wobble or shim every table leg to create a solid surface.  Some stamp patterns require very deep texture which makes it difficult when moving your chair away from the table or moving the BBQ.  Look at stamp texture skins for patios or consider colored concrete lightly troweled or broom finished.  Even a properly installed exposed aggregate can be more appealing to feet and furniture than a stamp pattern with very deep texture.  Stamp texture skins are patterns with no grout lines leaving the patio looking like free floating slate or stone texture and are one of the cheapest patterns available.  Past ACDI installed stamp patio designs combine broom / lightly troweled colored concrete bordered by a stamp pattern eliminating any concerns over furniture wobbling.  With the interior of the concrete patio being smooth and complimenting the border color, you can get a stamp concrete patio that is not only beautiful but practical as well.  

If you have concrete steps leading to French doors or to your front door, there are some limitations when it comes to picking a stamp pattern.  Most step treads (where your foot lands) are 16"-and under or 36"-and over in dimension.  The larger the stamp concrete pattern, the bigger the concrete step has to be in order for the pattern to repeat.  For example, any Belgian fan patterns are impossible to do on steps because there's not enough concrete surface in order to see the pattern on steps.  Sometimes, this narrows down the amount of patterns you can choose from so be aware that some patterns have limitations on steps.  

What creates the surface to shine?

You notice a "sheen" to all stamp surfaces--usually a sign that a acrylic concrete sealer has been applied to the surface.  Concrete sealer comes in a variety of "sheens" and plays an instrumental roll in protecting your concrete from stains, weathering and moss growth.  ACDI applies various acrylic sealers and offers annual cleaning and sealing services.  Depending upon the volume of foot traffic, re-sealing your stamp concrete ranges between every (2) to (3) years.  If you get more foot traffic than the average slab you may have to re-seal annually.  All exterior sealers ACDI installs include non-slip additives for additional traction.  

Customers can select from different types of sheen:  high gloss, satin and matte finishes.  Solvent based sealers contain xylene (also known as paint thinner) which intensify stamp and colored concrete.  Water-based acrylic sealers is another acrylic sealer that can be applied to stamp concrete, however, the lack of solvent keeps concrete colors bland and softer.  Initially, stamp concrete is sealed with what known as a "cure-n-seal" which has a shorter lifespan and is meant to help new concrete cure slower and keep stains from penetrating the color.  

Because new concrete hydrates water for 30 + days, applying a more durable sealer has to occur after the slab reaches 30 day strength.  Sealers with higher volumes of acrylic tend to peel and lift off the surface when applied too soon to new concrete.  "Cure-n-seals" last roughly 6-12 months (depends upon traffic), then you can apply a thicker acrylic sealer to your stamp and colored concrete.

For revitalizing damaged or weathered stamp surfaces, ACDI uses a combination of stains and tinted sealers.  So, if you have existing concrete that needs a facelift, call ACDI to see which decorative options suit you best.