Shop Smart Guide to Buying Integral Color and Color Hardener for Concrete"Too drab," are the words some uninformed consumers utter when comparing the attributes of concrete with those of alternative paving or flooring materials. Fortunately, with the multitude of products available today for coloring concrete, no one has to settle for lackluster gray. This is a key selling point for many decorative concrete contractors, which makes the selection of a coloring medium one of their most important purchasing decisions. Two of the most popular methods for coloring newly placed concrete are integral coloring admixtures and dry-shake color hardeners. Both infuse concrete with rich, long-lasting, fade-resistant color, and in the case of color hardeners, even improve surface hardness and durability. Stamped concrete contractors often use one or both of these coloring mediums to produce a backdrop for contrasting accent or antiquing colors, such as pigmented release agents and stains or dyes. This layering of color is what enables them to so closely replicate the variegated, multi-tonal appearance of natural stone. Other applications for these products include interior floors and concrete surfaces requiring extra wear and abrasion resistance. So which is the best method to use to take your next project from bland to technicolor? Here's a primer on the differences between integral color and shake-on color hardener and some of the advantages and limitations of each. We also give you tips for buying and using these products as well as pointers for achieving consistent color. Integral coloring admixtures are typically a blend of synthetic or natural iron-oxide pigments and surfactants (or wetting agents) that are mixed thoroughly into fresh concrete before placement to achieve uniform, homogeneous color. Integral colors are available in powdered, granular, or liquid forms. For convenience, contractors can order the color directly from the ready-mix supplier for addition at the batch plant. However, many integral color manufacturers have made it easier than ever for contractors to add the color to the truck mixer at the jobsite by packaging their dry pigments in premeasured quantities in disintegrating bags that can simply be tossed unopened directly into the mixer. Liquid pigments, which typically come in pails or buckets, are also easy to add onsite to the concrete mix. Advantages The biggest advantages of integral color are convenience and labor savings, says Bob Harris, president of The Decorative Concrete Institute and author of Bob Harris' Guide to Stamped Concrete. Because the integral color is mixed into the concrete, you can simply place and finish the concrete as usual. There's no need dust the color onto the surface and float it in during finishing, as is the case with shake-on hardeners. Another plus: Integral color is permanent because it extends throughout the entire concrete slab. So even if the slab surface is accidentally chipped, scratched, or abraded, the color will remain, unlike with surface-applied treatments. Manufacturers also say that the pigments in integral coloring admixtures are chemically stable and won't fade over time from exposure to the weather or ultraviolet light. The chief disadvantage of integral color is that the hues are more subtle and less intense than what you can achieve with color hardeners. You're generally limited to soft earth tones or pastel shades. In fact, iron-oxide-based integral colors are only produced in three basic hues: red, yellow, and black. Manufacturers concoct all the other shades, such as browns, tans, and mauves, by blending the basic hues in different ratios, says Chris Sullivan, national technical director and regional sales manager for QC Construction Products. The exception is blue and green tones, which are possible to produce but typically cost at least two to three times more than iron-oxide pigments because different mineral oxides are used, according to Sullivan. Cost can be another hindrance. Because you're coloring the entire batch of concrete, rather than just applying color to the surface, you'll generally pay more for integral color than for a shake-on color hardener. Integral color manufacturers also warn that due to the graying effect of most cements, some integral colors should only be added to concrete mixtures containing very light or white cement, which can further boost your overall costs.
Dry-Shake Hardeners Most shake-on color hardener manufacturers make blend pigments, portland cement, finely graded silica sand, and wetting agents. They come in powdered form, packaged in bags or pails, and are tossed or hand broadcast onto the fresh concrete. After the hardener wets up, a wood bull float is used to float the hardener into the surface before the concrete hardens. Unlike integral pigments, which color the entire concrete matrix, hardeners color only the top 1/8 to 3/16 inch of the slab. Decorative contractors often use dry shakes to color stamped concrete flatwork or concrete overlays, because the rich surface paste helps to produce sharper imprints. Advantages Dry-shake hardeners come in a wider array of hues than integral colors, including various shades of blue and green. And because the color is concentrated on the surface, it tends to be more intense. As the name implies, color hardeners also densify the concrete surface because they contain hard mineral aggregates and portland cement. The result is a surface that's stronger, more wear resistant, and less permeable to moisture and deicing chemicals than standard concrete. The two main disadvantages of color hardener are the labor and the mess, according to Jeff Potvin of Architectural Concrete Consultants. Most manufacturers of color hardener recommend applying color hardener in two separate applications, or "shakes," instead of applying the entire recommended dosage all at once. This gives the hardener a chance to "wet out," or absorb water. After each application, the hardener must be worked into the surface with a float. Potvin says that it usually takes six man-hours to spread color hardener on approximately 500 square feet of concrete. Because of their shake-on application, dry shakes generally are limited to use on horizontal surfaces. However, Harris says that you can apply them to step faces by combining the hardener with a bonding agent and water and then plastering this mixture onto the vertical faces with a trowel.
Weighing the Options When making side-by-side comparisons of integral colors and dry shakes, here are some additional factors to evaluate before making a decision: Generally, integral color will cost more than a dry-shake hardener because you are coloring the entire concrete slab rather than just the surface. But a dry shake may not always be the most economical choice if you factor in the additional labor involved to apply it and work it into the surface. Also remember that when using lighter shades of color hardener, you will need to use more product to get good results. Desired color effects If you want a greater selection of colors and more vibrant hues, then a color hardener will provide more options. With dry shakes, you can also apply accent colors of hardener to achieve contrast, using one shade as a base topped with as many as four or five different accent colors. Harris recommends using this technique on stamped concrete projects to replicate the subtle color variations you would see in natural stone. Although it's possible to obtain more vibrant pastel shades with integral color, doing so could be cost prohibitive because you would need to use a white cement and a higher dosage of pigment. Another option is to use integral colors in conjunction with surface-applied treatments-such as color hardeners and chemical stains-to create layers of color. If you can't find just the right color for your project, ask the manufacturer about the possibility of custom color matching. Suppliers of both integral color and color hardeners are often able to match existing color tones or formulate custom hues to suit your design scheme. Creating Samples Clark Branum, director of technical services for Brickform Productsadvises that creating samples or mock-ups of the work to be done are critical to the success of any colored concrete application. "Mock ups with integral color are typically expensive since a minimum of 3 cubic yards must be used to produce consistent color, partially due to the amount of cement paste it takes to coat the drum of a cement mixer. With color hardener, it is much easier to create small panels and mock ups that can easily be reproduced on a larger scale, making it much more cost effective during the front end phase of a project," says Branum. Jobsite considerations Dry-shake hardeners are not only labor-intensive, they also are messy to apply. Because some of the material goes airborne during broadcasting, it's necessary to protect adjacent buildings, landscaping, and existing slabs with plastic sheeting. This airborne powder can also be harmful to breathe, so it's important to wear a respirator or dust mask when working with these products. These issues aren't concerns when using integral color, since the pigments are mixed right into the concrete.
When applying dry-shake hardeners on extremely hot or windy days, you will also need to take measures to prevent moisture in the surface from evaporating too fast. Not only can this rapid moisture loss lead to surface crusting and cracking, it will make it impossible for you to properly wet out the color hardener. However, you can use an evaporation reducer, such as ConFilm from Degussa Admixtures and Eucobar from Euclid Chemical, to help slow surface moisture loss on hot, windy days. Performance Because color hardeners improve the strength and density of the concrete surface, they often are a good choice for exterior slabs exposed to freeze/thaw cycles and deicing salts and for interior floors exposed to heavy traffic and abrasion. Integrally colored concrete will have the same surface strength as standard concrete, but the color is permanent because it penetrates the entire slab. So even if surface abrasion occurs, the color will not wear away. Other Resources on the Concrete Network:
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