One of the most sustainable flooring types that is gaining acceptance lately is the polished concrete floor.

Why is it considered sustainable? well for starters, we save on resources. Why use expensive tiles or stones on top of a perfectly good concrete slab. Polished concrete floors do not require any voc spewing glues and adhesives needed to fix carpets or tiles and hence contribute towards improving the indoor air quality.

Polished concrete floors are being increasingly used in educational, commercial/retail, industrial and even residential projects. There are a lot of interesting examples of concrete floors if you search online. I specially like the acid stained polished floors.

So what is a polished concrete floor anyway? Lets look at the basics.

A polished concrete floor put simply is a polished concrete floor. It's that simple. But we do need to keep a few things in mind before specifying one. First and foremost is the quality of concrete slab we want to polish. Strength of concrete is important and a minimum of 4000psi concrete is recommended for an architectural polished floor. Flatness of concrete floor is another important consideration and will impact the type of look we want. Speaking of the look- polished concrete floors are categorized into 3 grades and 3 classes. Grade of concrete floor determines the look of the floor and class determines the level of polish .

The 3 grades are:

• Grade I (cream finish): requires a very flat slab to begin with. In Grade-I slabs, none of the coarse aggregate is exposed while grinding resulting in a very consistent tone.
• Grade-II (Salt n pepper): requires a little bit more grinding resulting in some exposed aggregate hence the salt n pepper name.
• Grade-III (aggregate finish): As the name suggests, this grade of floor requires a little extra grinding to expose the aggregate resulting in a terrazzo like finish.

The 3 Classes are:

• Class-I: Low reflectivity
• Class-II: Medium reflectivity
• Class-II: High reflectivity

Another consideration in a polished concrete floor is color. Color could be integral (mixed with concrete mix) for new projects or could be surface applied for both new and existing concrete slabs. In the case of surface applied colors, chemical stains (aka acid stains) provide a very interesting but unpredictable pattern. Chemical stains react with concrete to produce colors and hence result in an organic (or mottled) appearance. Chemical stains are available in earth tones. For indoor applications surface applied dyes can also be used and are available in a greater variety of colors.

Polished concrete floors look great, last a long time, age gracefully and cost a lot less than many other flooring materials ('sasta, sundar aur tikau' for my Indian friends). If you have used concrete floors in any of your projects please share your experience and pics.

Further resources:

http://en.wikipedia.org/wiki/Polished_concrete

http://www.scofield.com/architects/

http://www.concretenetwork.com/concrete/polishing/