Concrete flooring: Some hard-and-fast facts By Jason Blackshaw

Concrete is regarded as an important basic building material. It is used for practical purposes such as creating strong, enduring exteriors, reinforcing girders, and solidifying structures.

ADELLE PROJECTS (photo credit: ADELLE PROJECTS)
ADELLE PROJECTS
(photo credit: ADELLE PROJECTS)
Concrete is regarded as an important basic building material. It is used for practical purposes such as creating strong, enduring exteriors, reinforcing girders, and solidifying structures.
But concrete can also be used as a means to enhance interior design. It can be polished in the same was as marble or granite to create glossy flooring.
Polished concrete floors are advantageous in that they can cover large spaces in contrast to marble or granite floors, where the slabs are limited in size. With polished concrete floors, interior decorators can create seamless flooring. Polished concrete floors are very practical because they last long. And used on large surfaces, they are more economical.
A historical perspective
Polished concrete floors were introduced commercially in the 1990s, but they actually existed many years ago. The earliest known concrete floors were discovered in our part of the world. When the Israeli Transport Ministry was building a new road in the Jordan Valley, several layers of concrete floors were found in Jericho and the surrounding settlements, some of which were polished concrete.
The modern use of polished concrete had to wait several millennia. It came into renewed use by accident. In 1992, a natural stone polishing contractor who was starting work on a palatial residence in Tunisia instructed his crew to polish a concrete floor. Assuming that they knew it was to be polished wet as was customary with marble, granite or natural stone, he left them to do the task. When he returned several hours later to check on their progress, he realized that they were dry polishing the concrete and was surprised to see how beautiful the floor looked. And that was the beginning of the trend of polished concrete floors.
 
A multi-step process
Polishing concrete is a multi-step process, tells us Nathan Guetta, CEO of "Adelle Projects". A concrete floor is mechanically ground, honed, and polished with bonded abrasives to cut the floor’s surface. With each cut, it is refined to achieve a specified appearance.This process includes the use of a penetrant chemical known as a hardener. The hardener penetrates into the concrete and creates a chemical reaction to help harden and dust-proof the surface. During concrete polishing, the surface is processed through a series of steps utilizing progressively finer grinding tools. (Generally, a minimum of four grinding steps of processing is considered polished concrete.) The grinding tools are progressive grits of industrial diamonds in a bonded material such as metal/hybrid/resin, often referred to as diamond polishing pads.Polished concrete is an eco-friendly flooring system and is LEED-approved (Leadership in Energy and Environmental Design). Concrete is not considered polished before 400 grit, and it is normally finished to the 400, 800, 1,500 or 3,000 grit level. Dyes designed for concrete polishing are often applied to add color. Other options include scoring, creating radial lines, grids, bands, borders and other designs.

Photo credut: adelle projectsPhoto credut: adelle projects
The pluses of poilshed concrete
Polished concrete floors have many advantages. They are  low maintenance, as they are durable and easy to clean. Their high coefficient of friction makes them non-slippery. Polished concrete reduces dust mite and allergen problems and does not support mold growth. Highly reflective polished concrete also reduces the need for artificial lighting and can enhance natural lighting. Polished concrete flooring is hard wearing and will not chip or dent like softer surfaces such as ceramic tiles or wood. Polished concrete is easily maintained with the use of clean water or a neutral balance pH cleanser. There are also many cleansers designed for the maintenance of polished concrete. There is no need to wax the floor, as it would dull the finish. A concrete floor that has been hardened and polished will have an extremely long life expectancy compared to other types of flooring. Concrete structures can have a lifespan of more than 100 years. In simple terms, the process of polishing concrete is similar to sanding wood. Heavy-duty polishing machines such as concrete grinders are used to gradually grind down surfaces to the desired degree of shine and smoothness.
Installing the floors
Polished concrete floors can be installed in two forms:
  • As new flooring 
  • In existing floors
New floors require less work, resulting in lower costs. But there are several things to be aware of before a new concrete floor can be polished. Firstly, the mix design of the concrete should be 3,500 psi or higher. The concrete should always be poured full depth to take advantage of the concrete’s structural strength and help prevent cracks. The concrete should be professionally finished with power trowels and properly cured with water for seven days. Polishing should not begin until the concrete is fully cured (generally 28 days).
The concrete slab can contain decorative aggregates to create various esthetic appearances. The finished surface of the concrete must be finished to a high standard to facilitate the polishing process. During the finishing phase, decorative aggregates such as seashells, glass chips or even metal car parts can be dropped into the surface of the concrete.
Existing concrete floors can be polished in a number of ways, depending on the condition of the concrete. If the concrete is in good condition, the surface can be polished to just about any standard. If the floor slab is in poor condition, it can be cut or ground, and the natural aggregate can be featured as the exposure level. If the surface is in poor condition, a slab with a minimum thickness of 50 mm. can be placed on top.

Photo credut: adelle projectsPhoto credut: adelle projects

On the local scene
Polished concrete flooring is gaining popularity in Israel. It is used widely in institutional buildings with large floor areas such as banks, hospitals, and government offices. But it is also gaining in popularity in private residences, mainly in large single-family homes and spacious penthouses.
the article was written in association with adelle projects