Reactive stains, also called acid stains or chemical stains, are used to penetrate the top layer of cured concrete to create translucent colors. The metallic salts in the stain materials react with calcium hydroxide in concrete, commonly called "free lime," producing earth-toned colors that are characteristically variegated and somewhat unpredictable. The acid-stained concrete colors are typically permanent when correctly applied and neutralized. Very old concrete may be deficient in free lime and therefore more difficult to chemically stain without applying an accelerant. (If a variegated appearance is not desired, dyes or water-based stains offer an alternative that produces predictable translucent colors on concrete with a more uniform appearance. Dyes and water-based stains come in a wider range of colors and are nonacidic, so they do not require neutralizing and washing.)
Bond matrix is what determines if the floor will eat your diamonds or just be cut. So pay attention here. Developing just one bond matrix to handle every level of hardness is impossible. To process the floor efficiently, a soft bond should be used on hard concrete and a hard bond on soft concrete. When polishing is done right, maximum refinement will be achieved with the fewest rotations over the surface.
Also called dry-shake color hardeners, the powdered coloring materials are broadcast on freshly placed concrete to create a colored horizontal surface with improved density. This coloring method can produce more intense, opaque hues than integral coloring. Typically, color hardeners are a mixture of pigments, mineral aggregates, graded silica sands and portland cement. Use of color hardeners is most popular for exterior hardscapes in areas subjected to freeze-thaw cycles and deicing salts. Some contractors prefer to stamp concrete that has been colored in this method because the rich paste created when the color hardener is worked into the top layer of the concrete surface holds a sharply defined imprint.
Cometing refers to the comet trails that are visible on the face of the diamond bond. You can glean from a visual inspection that the diamond bond has been opened at the factory. The amount of cometing shows how rich or full the diamond bond is with diamonds. Manufacturers can lower the cost of a diamond bond segment by reducing the amount of diamonds. Less diamond grit means less cometing. Cometing also signifies that the diamond bond has not glazed over, or closed, to a point where no grinding will be realized.
A specialty area within concrete construction wherein skilled contractors employ creative methods of finishing existing or new concrete with stains, colors, designs, textures and patterns that make it more aesthetically appealing when it is visible. Decorative concrete contractors makes concrete an attractive choice beyond its functional and structural role in construction. Decorative concrete has become popular for hard landscaping and features for patios, sidewalks, porches, pool decks, retaining walls and other exterior amenities. There is growing demand for the use of decorative concrete for interior floors, counters, sinks and tubs, fireplace surrounds and even attractive interior walls. Knowledge of best practices for basic concreting contributes to successful decorative concrete projects. In the past decade, decorative concrete has been used more and more often in the building industry because concrete is considered an environmentally sound building material that is produced from abundant local materials that can be mined with minimal disruption. It can also be recycled after use. Concrete has historically proven to be a durable, strong and versatile material, especially when combined with reinforcement. Ancient Roman structures, such as the Pantheon, are proof of the superior durability and longevity of concrete.
Colorless materials applied to concrete to harden the surface and reduce dusting. The products offered for densification are typically proprietary materials containing silicate, siliconate or blends of the two. Densifier application is sometimes used when finishing concrete by coarse grinding, but is essential for polishing the concrete to a highly honed sheen called polished concrete. Integrally colored concrete may be densified. When stains and dyes will be used on densified concrete, consult with the densifier manufacturer for compatibility information. Some densifiers are not intended for use with colored concrete and may cause lightening or discoloration. See also Grinding and Polished concrete.
Diamond ratio determines how effectively a diamond bond matrix will last and cut. For example, 30/40 grit will have a certain ratio of 30-grit to 40-grit diamonds. Mixing the grits keeps the diamond bond matrix open, allowing for a continuous and effective cut.
A discoloration on the surface of concrete that can be caused by evaporation during curing. Calcium hydroxide reacts with carbon dioxide in the air to form calcium carbonate, a white crystalline deposit. The residue can be left to wear away from the effects of weather or can be removed. Contractors can use various methods to reduce the incidence of efflorescence. Although efflorescence is typically superficial and harmless, it detracts from the beauty of colored concrete.
Concrete engraving is the act of remodeling existing (cured) concrete by cutting patterns and texture into the surface. Decorative concrete engraving adds depth and dimension. Plus, it is commonly used as a color separation technique. In general, the result of engraving may be a decorated object in itself, as when silver, gold, steel, or glass are engraved, or may provide a plate for printing images; these images are also called engravings.
Coarse grinding and medium grinding are done mechanically to clean up a concrete surface or expose aggregates. The concrete surface can be coarse ground when wet or dry to renovate an interior floor or exterior hardscape. Grinding is done to remove unwanted residues such as glue, coatings or paint, as a preparation step prior to staining. Grinding can also be done in order to improve adhesion before applying a coating or overlay.
A spray gun with a hopper attached. The air-driven tool is used to spray polymer cement materials onto concrete surfaces in a splatter pattern. See also Knockdown Finish.
The process of mixing pigments or coloring agents into concrete or cementitious materials such as toppings and overlays
Integrally colored concrete
Colored concrete created by adding coloring formulations, inorganic iron oxide pigments or dyes into a concrete mix. Either dry powder, granules or liquid suspensions of pigments are introduced when the batch is in the mixer or ready-mix truck. Some integral-coloring materials contain additives that may or may not be compatible with other materials. The mixing distributes the color throughout the batch. The benefit of integrally colored concrete is that the slab looks good long-term because any gouges, scrapes or chips reveal concrete that is also colored the same as the top surface.
Job-site mockups vs. samples
Mock-ups are produced by contractors to show alternative approaches to a project and provide a color reference for review. Using the local concrete aggregates, sands, cement and mix design specified for a project, and having the materials colored, treated, finished and sealed in exactly the same way the contractor will handle the project, a representation of what the finished decorative concrete piece ought to look like is produced for approval. It is common to review several sets of mock-ups that are at least 2-foot by 2-foot panels as a method for quality control. Manufacturer's samples are not produced using the concrete and methods found on the job site. Small samples ranging in size from 2 inches square to 12 inches square cannot provide an accurate representation of the inherent textural variations of concrete. Many mass-produced manufacturer's samples use a cementitious material instead of concrete as a color guide, so they will not always offer an accurate match. It is important to understand the distinction between job-site mock-ups and manufacturer samples.
A lightly troweled finish created when splatter patterns left after the use of a hopper gun are flattened to produce an attractive surface with good traction, but no sharp points of dried cement materials. See also Hopper gun
Composite rubber, plastic or urethane tools produced from molds that are used to apply continuous texture to freshly placed concrete. Typically the mats come in a variety of styles and sizes that can be used to produce shallow, low-profile continuous textures that look similar to stone, slate and other surfaces commonly used for flatwork and vertical features. See also Stamping concrete.
Generically, the term means an aged appearance produced by natural weathering and wear over many years, commonly seen in wood, leather and other materials. Stains are sometimes used on concrete with the intent to quickly produce a "patina" that seems aged. Products called patina chemicals are available to apply onto colored or stained concrete to make the weathered look more dramatic. See also Acid-stained concrete.
Composite plastic or urethane tools that are used to make impressions in freshly placed concrete. Produced in molds, the tools come in a variety of weights, sizes and styles, some of which look like individual stones of a specific style. Typically pattern tools, including both rigid platform tools and flexible tools, are sold individually and in sets. Examples of patterns include fans, tiles and bricks. See also Stamping concrete.
Stamp tools of composite plastic or urethane that are designed to support the weight of workers who stand on the tools to work their way across the width of a concrete placement while placing additional stamps and tamping the pattern evenly. The tools create pattern impressions in freshly placed concrete. Typically, placement of the patterns requires planning and detailing to skillfully replicate the look of unit pavers or hand-cut stone. See also Stamping concrete.
Also referred to as a tamper, the pounder is used to tamp the tool into concrete during stamping to produce an even impression of the patterns. Contractors sometimes stamp their feet to tamp stamps, but the results produced are not as consistent as results produced using a pounder or tamper tool. See also Stamping concrete.
A finishing method that produces high-sheen concrete surfaces. The polishing process involves the use of heavy equipment with discs of different "grits" to grind concrete in order to produce a more durable wear surface. The final finish appearance is quantified based upon the grit of the last head used during a grinding and polishing sequence. It can range from 150 grit to 3,000 grit. See also Densifiers
Also called bond-breakers, these materials are used to aid the smooth removal of stamping tools and keep tools from sticking to concrete, which could cause the pattern or texture to be marred. Typically, the liquid or powder release agents are applied both to the tools and the concrete surface prior to stamping. Release agents are available in both colored and uncolored products. See also stamping concrete.
Products used when designs or patterns are being applied onto cured concrete surfaces. A resist prevents stains or dyes from penetrating selected areas.
Materials added to concrete to delay setting. They are particularly popular in warm climates. Consult manufacturers' recommendations for compatibility when planning to use decorative concrete coloring materials such as stains, hardeners or colored release agents on concrete that will contain retarders.
Sand-blasting and shot-blasting
Sand-blasting, like shot-blasting, involves propelling uniform particles against a surface at high velocity. Sand-blasting was originally developed for cleaning the surfaces of buildings. Today, grit, slag, shell, and other materials have replaced the use of silica sand to avoid the risk of silicosis. The process of sand-blasting can be used for decorative purposes to etch a pattern or design into a concrete surface. For example, during template sand-blasting some areas are covered with a mask, and uncovered areas are sand-blasted or shot-blasted to reveal the aggregates below the surface. Sand-blasting and shot-blasting are also commonly used for surface preparation prior to the application of coatings or toppings.
Sealing is a recommended step for enhancing and protecting decorative concrete colors. Sealing decorative concrete reduces maintenance requirements and helps prevent unwanted staining. Both water-based and solvent-based formulations can be purchased. Some sealers are available in finishes such as gloss, semigloss and matte.
Sintering is creating objects from powders, and whether to do hot or cold sintering is an engineering decision. When done correctly, it creates a diamond bond that is solid and will not fracture nor fall apart.
Thin, flexible, composite rubber, plastic or urethane texturing tools, also known as embossing skins. Skins can be bent more easily than mats for use on edges, steps and awkward corners. Skins are an efficient way to quickly apply textures to large areas in warm conditions where concrete is setting rapidly. Like mats, skins come in a variety of styles and sizes. They can be used to produce shallow, low-profile continuous textures that look similar to stone and other surfaces when stamping horizontal areas or producing artificial rockwork. When applying a continuous pattern, flexible skins require somewhat less time and planning than using interlocking stamp patterns.
Some stains, sealers and coatings are manufactured using solvents as the carrier for the liquid mixtures. During application, solvents evaporate into the air. Therefore, solvents are considered "volatile organic compounds," or VOCs, and it is vital to adhere to the manufacturer's health and safety recommendations during application of any solvent-based product. An MSDS (Materials Safety Data Sheet) will document the percentage of VOCs in a specific product. Please note: The specific percentage of VOCs permitted is regulated in most areas of the United States and Canada. The use of solvent-based products is prohibited in some states. Where environmental considerations prohibit use of solvent-based materials, water-based alternatives are readily available.
Stamped concrete or imprinted concrete is created by pressing pattern tools or texture skins into freshly placed concrete at the stage in hardening when the concrete is at a "plastic-like" state that will take the pattern impression. Colored release agents can be used to provide greater realism by accenting the details the pattern leaves in the concrete. See also Release agents.
Also called templates, stencils are used as masks in a variety of ways when transferring superficial patterns or designs to the surface of cured concrete. Different colors or materials can be applied alternately in the "positive" and "negative" areas of the stencils using stains, dyes, dry-shake hardeners or spray-applied polymer cement toppings. Also, the stencils can be used for etching or sand-blasting. Both off-the-shelf and custom-designed stencils can be ordered. Some standard stencils resemble the mortar joints between stones, tiles or bricks, and ornamental motifs similar to borders on rugs and wood flooring are also available. Typically, stencils are produced in adhesive and nonadhesive rolls or sheets made of acetate, cardboard, paper or Mylar. Manufacturers who regularly supply in large quantities produce their stencils using a computer program and plotter. Some artisans hand-cut their own custom stencils from metal, plastic wood or any handy materials.
A spiked tool used to embed stencil material into fresh concrete.
A tool with a raised texture that can be used to roll over freshly placed concrete to leave a shallow impression. The texture roller can be used on the entire surface or combined with a stencil to leave texture in only the "negative" areas of a stencil pattern.
A descriptive term that refers to the varied, mottled effects produced by reactive chemical stains on concrete. Typically the variegation of specific surfaces in combination with specific stains produces unique and somewhat unpredictable results. The variegation can be altered by the method of application and the colors selected.
Some stains, sealers and coatings are manufactured using water as the carrier for pigments or other materials in the products. Water-based and water-borne stains and sealers are readily available for use where environmental considerations are a priority.
When a stain or other coloring material is topically applied to concrete, the time needed to complete the reaction or the bonding is referred to as working time.
To remove the negative areas from the stencil after it is applied to the cured concrete.