Exposed aggregate has been here a good 30 plus years. It’s nothing new. However, the evolution of exposed aggregate concrete is fascinating. In the beginning, exposed aggregate was achieved by washing off the surface of the concrete before it set up, and a bit later people used acid to expose aggregate, and others used good old fashioned cola (no joke, the sugar in the soda actually retards the surface!). As you can imagine, the results varied - and so has the reputation and popularity of exposed aggregate.
Traditional exposed aggregate concrete
Thankfully, the science and expertise in the industry has transformed this finish into something more predictable and consistent. With the use of surface retarders or deactivators, experienced contractors can now dial in the level of the exposure and produce more consistent exposed aggregate finishes. People can now get everything from extremely coarse aggregate exposure to a light sand - acid etched finished concrete through the use of surface retarders. A surface retarder is a liquid that is sprayed on the surface after the concrete is troweled smooth but before it is hard. There is still a timing element to it, but the chemistry in the retarder is pre-guaged to the desired level of exposure. The surface deactivator or retarder slows down the curing of just the top layer of the concrete. This slowing down of the curing allows the entire slab to cure as designed, but leaves the very top surface soft. Then, either later that day or the next day (depending of time of pour and the weather), the top layer (the skin of the concrete) is washed off to expose the sand and/or rock in the concrete - providing a consistent exposed aggregate concrete finish.
Rose Mirror Exposed Aggregate
Because of this evolution in the exposed aggregate finish, this now opens the door for even more creativity. Hence why we launched our Mira line. Mira takes the beauty of exposed aggregate concrete and allows everyone to customize the finish to their specific project. With Mira, you can create customized exposed aggregate concrete by adjusting the colors and even adding in your own choice of rock or recycled glass to be exposed. The possibilities are limitless! Design your own decorative exposed aggregate concrete today on www.miraconcrete.com.
Custom decorative exposed aggregate concrete