Concrete has been used in construction work since ancient times. Romans have combined quicklime, pumice aggregate and pozzolanic ash to create Roman concrete. The Roman Empire has extensively utilized concrete in the construction of buildings, monuments, aqueducts, and similar grand structures. Centuries passed and concrete has remained as a mainstay of construction due to its strength and durability. Hence concrete has been known as a utilitarian medium for construction rather than for decorative uses.
The use of concrete for decorative purposes is gradually gaining popularity. The transformation of concrete from a simple construction material to something that is aesthetically pleasing yet functional is made possible through the addition of chemicals and utilization of various techniques designed to create a certain effect. Decorative concrete is achieved through several methods such as stamped concrete, concrete dyes, acid- and water-based staining, overlays, epoxies, polishes, engraving, and form liners.
- Stamped concrete. A variety of colors and textures can be added to concrete to make it look like natural brick, cobblestone, slate, stone, fossils, shells, and wood. Usually, molds are pressed into fresh concrete and coloring agents may be added. Stamped concrete looks great on walkways, driveways, interior floors, and parking lots.
- Concrete dyes. Early concrete dyes came in the form of printing inks dissolved in alcohol and applied to the concrete surface. However, exposure to direct sunlight causes the color to fade. Hence most concrete dyes are limited to interior areas away from direct sunlight.
- Acid-based staining. By combining water, mineral salts, and hydrochloric acid and applying it on the concrete surface, unique and interesting patterns can be achieved. This is caused by the acid solution reacting with the lime content of concrete.
- Water-based staining. A special stain coat is applied to the concrete surface, providing a translucent or opaque effect. This coating may be polymer-, acrylic, or epoxy-based.
- Concrete overlays. Concrete may be mixed with aggregate and polymer resins and applied as a thin coating on top of existing concrete surfaces. Concrete overlays can be utilized to make concrete surfaces more resistant to damage caused by salt, oil, ultraviolet light, harsh weather, and heavy foot traffic. In addition, concrete overlays can be used to repair worn out and settled concrete surfaces.
- Epoxy treatment. Stained, dyed, and overlaid concrete surfaces can be further protected by the application of epoxy sealants to keep water out. Colored epoxy sealants are available to match the color of the concrete surface.
- Polished concrete. Concrete surfaces can have a polished glass-like polish through the use of mechanical grinders and diamond pads. Depending on the surface, polishing may take place in stages.
- Concrete engraving. Various lines and geometric patterns can be created on existing concrete surfaces by using various engraving tools such as an angle grinder.
- Urethane form liner casting. Concrete designs can be formed using urethane form liner casts. A urethane cast of the desired design is created. This acts as the cast where the concrete will be formed against. The cast is stripped after the concrete has set.