Concrete overlay is a method of covering an existing concrete surface with a very thin, new, layer of specialized concrete. It is applied as a broom finish to rejuvenate a worn-out cracking floor to give it a brand new look and enhance the existing dull concrete surface. Concrete overlays have an advantage because they can be applied over an existing concrete surface to create a new look, only limited by one's imagination. Overlays have unlimited variations of color and texture and can be stamped, squeegeed smooth, troweled, sprayed, and broom finished. Overlays have been available for 3 decades, and come in many forms: Stamped Concrete Overlays, Microtoppings, Self-leveling Overlays, and Spray Applied Overlays. Each form has its own application method which allows the concrete contractor to be creative with the final presented design.
Stamped Concrete Overlays
Stamped concrete, often called textured or imprinted concrete is concrete that replicates stones such as slate and flagstone, tile, brick, and even wood. Stamped concrete overlays can be one of the best ways to add an innovative and attractive touch of decoration to indoor and outdoor flooring.
The stampable overlay systems are applied in thickness ranging from 1/4 to 3/8 inch thick then stamped with texture mats to resemble stone, slate, brick, etc. The common thickness is 3/8 inch, which is usually thick enough to accommodate most standard imprinting tools in the market place. Stampable overlay systems are designed to be applied with a gauge rake, quick trowel smoothed and then imprinted with the desired texture or stamp tool. Either a powder or liquid release material can be used, depending on the final look and/or color scheme that is desired. These materials cure in 24 hours, and can usually be sealed and light traffic allowed within 36 hours after application. The single most important factor with any stampable overlay application is surface preparation. The surface needs to have a sufficient profile (be rough enough) so that the overlay material can bond both chemically and mechanically.
Stamped concrete has the potential to become a popular choice for many homeowners because it offers a wide array of options when it comes to concrete patterns and concrete colors. Another factor contributing to its popularity is its price. The cost of stamped or imprinted concrete is often considerably lower than the materials it is a substitute for.
Micro toppings
Micro toppings are specialized overlay materials that are designed to be put down in very thin coats. They are used primarily to refresh (usually interior) surfaces that are very sound but are old and discolored. A new layer allows for easy staining and rejuvenation.
Micro toppings are a thin layer, no thicker than 1/8 inch, applied with trowels or brushes depending on the final look. They utilize "beefed up" polymers that allow the material to go down very thin and yet maintain strength, durability, and abrasion resistance. Micro toppings do not have the flow characteristics or sufficient mass of material to flow and so are not considered self-leveling. These materials are so thin that they dry very fast, so the final texture is limited to how the micro-topping is applied over the concrete floor. This alternative cure in a day, and usually could be walked over within 36 to 42 hours of being applied. It is important to seal micro-topping finishes, as they are microporous and will tend to collect dirt that is difficult to remove once embedded into the material. Micro toppings can be used on interior and exterior surfaces, residential and office, and floors, lobbies, retail walls and floors, decks, patios, ceilings, countertops, showers, masonry, bleachers, food concession areas, waterparks, sidewalks, and driveways.
Micro toppings also offer the most variation in regard to color and finishes. They can be applied plain, colored integrally, or be topically colored with stains and dyes. The ability to manipulate the look of a micro-topping to create a wide range of finishes and colors is a big selling point.
Self-leveling Overlays
Self-leveling overlay systems for concrete floors offer numerous advantages. They can correct uneven floors, repair damaged concrete, and provide a smooth and durable new surface for decorative treatments. These flowable polymer-modified toppings have the ability to self-level without troweling, making them a quick solution for smoothing and leveling worn or uneven concrete.
Self-leveling overlays are simply poured or pumped onto the floor surface and then distributed evenly using a spreader. As with other types of overlay systems, proper surface preparation is critical to ensure a strong bond. Most self-levelers are typically applied at thicknesses of 1/4 inch or greater, allowing them to effectively cover minor flaws and compensate for height variances. Self-leveling concrete could be combined with dyes or tints to create wonderful finished colors.
The self-leveling concrete overlay could be a very expensive solution, but the results are far better than other alternatives. Self-leveling concrete material could be divided into two main groups: Underlayments and Toppings. Underlayments are installed over an existing subfloor to smooth it out and correct any surface irregularities prior to the installation of all types of floor coverings; while Toppings act as the actual finished floor without the need for a floor covering.
Spray Applied Overlays
Versatile and easy to apply, spray-down concrete systems offer a wide array of finish options. Usually, they are sprayed evenly onto concrete with an air-powered hopper gun, but they can also be applied as a splatter coat to create a textured, slip-resistant surface or "knocked down" with a trowel to create a smoother finish. They are very similar to micro toppings in that they are thin, but differ in that they usually contain more sand and provide a rougher, grittier finish.
These systems are often used for concrete pool decks and patios to give them a decorative slip-resistant finish. They also are a good option for high-traffic interior floors because of their durability, low cost, ease of application, and range of patterns and colors. A popular decorative technique is to use paper or adhesive stencils to produce designs such as borders and medallions, tile patterns, and embossed or inlaid motifs
