Aggregate exposure classes describe how much stone shows on a ground or polished concrete floor. Cream shows mostly smooth cement with little stone. Salt and pepper shows fine sand specks. Full aggregate shows larger stones for a terrazzo-like look. The class is set by how deep the floor is ground and is chosen separately from how shiny it is.
The Three Polished Concrete Aggregate Exposure Classes
Grinding a slab is like slicing the top off a chocolate chip cookie. A thin slice shows mostly dough, a little deeper shows specks, and deeper still shows the chips. The industry’s aggregate exposure chart names three classes:
- Class A, cream: Mostly smooth cement paste with a few tiny specks. It has a clean, uniform, modern look.
- Class B, salt and pepper: Mostly fine sand showing through, with a scattering of other bits. It reads as a speckled, granite-like texture.
- Class C, full aggregate: Mostly larger stones showing, for a look similar to terrazzo.
Exposure class is separate from sheen level. You can have a satin cream floor or a highly polished full-aggregate floor.
What Decides How Your Floor Will Look
What shows depends on what’s in the slab. The size and spread of aggregate at the surface come from how the concrete was mixed, placed, and finished, and flatness matters too. On a wavy slab, the grinder cuts deeper on high spots, so you can end up with full stone in one area and cream in a dip.
Color can shift as well. The same floor can look gray at the cream layer and turn brown once sand and stone are exposed. Deeper cuts also take more grinding and can open up small holes and flaws that need filling, which adds cost.
Choosing an Aggregate Exposure Class
Cream suits people who want a smooth, even look. On an existing slab, ask your installer whether patches or uneven spots will make an even cream finish realistic. Salt and pepper is a common middle ground. Full aggregate gives the most stone but costs the most and depends heavily on the stone already in the slab.
For new construction, decide early. The concrete crew can place and finish the slab with your target class in mind. Our guide to polished concrete floors covers how this fits with sheen and cost.
Aggregate Exposure FAQ
Can you expose aggregate on existing concrete?
Yes, grinding can expose the sand and stone already in an existing slab. You can only show what’s there, though, and you can’t choose the stone color or size after the fact. A test area tells you what your slab will reveal.
What is salt and pepper polished concrete?
It’s the middle exposure class, where grinding goes just deep enough to show fine sand specks across the floor. It gives a subtle, speckled look without big stones. It’s popular because it works on many existing slabs.
What are the downsides of exposed aggregate polished concrete?
Full aggregate takes the most grinding, so it costs more and can turn up holes and flaws that need filling. Results depend on the stone already in the slab, so the look can vary from room to room. Cream and salt-and-pepper finishes are quicker and more predictable.