Since venturing off to start The Art of Concrete with my business partner, Ryan Lakebrink, I have learned more about polished concrete than I ever realized I didn’t know. And I know there is so much more to it that I have yet to learn. It is such a beautiful medium that embraces the beauty of concrete. Concrete is beautiful in its natural form. One of the reasons I love exposed aggregate and/or sand finish is the same reason I’m falling in love with polished concrete. It celebrates the ingredients of the natural material. In the finished product you see the cement and aggregates in the most refined form.
One of the most important things I have learned so far from the CPC (Concrete Polishing Council) is the different classifications that define polished concrete expectations. For polished concrete there are 3 “classes” and 4 “levels”.
The “levels” define the image clarity – or how reflective the floor is. The higher the level, the more reflective it is. Level 1 is more of a flat/matte finish, while Level 4 is highly polished and almost mirror-like. Level 1 is rarely speced and Level 4 usually required grouting in order to fill pin holes in the concrete which would distort the reflectiveness of the floor if they were left open. Level 3 is the most common level.
The different “classes” of the floor helps define the aggregate exposure. A Class A floor is made up of mostly cement fines and minimal aggregate exposure. This is called either a cream finish or cement fines finish. It can be beautiful, but is very hard to achieve and the floor needs to have high FF (floor flatness) levels in order to pull it off successfully. A Class B floor is the industry standard (along with Level 3) and is called either a fine aggregate or salt and pepper finish. This class exposes the fine aggregates/sands within the mix. There may be up to 5-15% of coarse aggregate or cement fines, but the majority of the floor is a sand exposure. The Class C finish exposes mostly coarse aggregates (the chunky rocks in the mix of concrete). This floor is a little more forgiving with consistency, so the FF numbers can be a little lower since the polisher is grinding off more of the surface to get to the larger aggregates. There still may be a 10-20% blend of the cement and fine aggregate exposure, but the overall floor will be made up of the coats aggregate. Below is a picture version of our polished concrete sample board that gives you a snapshot of the classes and levels (level 1 is not shown). If you are an architect in Colorado and would like one of these boards (since photos don’t do it justice to really see the difference in levels), please contact us.