Aggregate Exposure Levels
There’s a time-honored adage about concrete which states that concrete is consistently inconsistent. Every single pour will be different from the next, with variations in color, cracking and overall flatness. While the polish finish is the end-game for custom concrete applications, aggregate exposure in custom concrete flooring can add a dimension of beauty and interest to the finished product.
Concrete aggregate exposure is popular with architects looking for a flooring option that offers design flexibility at a lower cost than terrazzo. The polishing process usually includes grinding down the concrete surface to reveal different levels of aggregate within the concrete or the addition of decorative aggregates, such as recycled glass, landscaping stone, and others, seeded into the surface for decorative purposes. Depending on the diamond grit used to prep a polished concrete floor, different levels of aggregate exposure can be achieved.
The Five Levels of Aggregate Exposure
| CLASS | NAME | APPROX SURFACE CUT DEPTH |
APPEARANCE | EXAMPLE |
|---|---|---|---|---|
| A | Cream | Very little | Minimal exposure of fine aggregates or sands. A high level of flatness and floor levelness is required to maintain a uniform appearance. |  |
| B | Fine aggregate (Salt and Pepper finish) | 1/16 inch | Fine aggregate exposure. Cut depth of ~1/16 of an inch exposes fines and sand; no larger aggregate seen. |  |
| C | Medium aggregate | 1/8 inch | Medium aggregate exposure with little or no large aggregate exposure at random locations. Cut depth of ~1/8 of an inch exposes small to medium aggregate. All surface paste is removed. |  |
| D | Large aggregate | 1/4 inch | Large aggregate with little or no fine aggregate exposure. Cut depth of ~1/4 of an inch, exposes coarse aggregate similar in appearance to terrazzo. |  |
| — | Random Exposure | 1/4 inch | Cut depth of ~1/4 of an inch, exposes aggregate variations. |  |
