When laying exposed aggregate around your home, you'll need to choose decorative stones or other embellishments that you want to add. Pebbles come in many colours: blue, sand, cream, red and grey, which you can mix or match to create uniform or colourful concrete.
You'll also need to consider whether to choose rounded or angular stone, which will generate smooth or sharper surfaces, respectively. Your selections will depend, among other things, on whether you intend to walk across it in bare feet, as you might want to for a pool deck or patio.
Once you've decided what to add, your contractors will need to get to work creating your design. There isn't only one way to do this; they can perform different processes. Read on to discover three main methods contractors use to incorporate the embellishments across the concrete, plus, how they'll expose them.
One way is to add the aggregates to the cement mix before pouring. This method uses the most aggregates as they disperse throughout the entire concrete, some of which may be submerged and thus not visible.
An overlay provides a smart way to distribute the aggregates while using fewer of them. Instead of dispersing them throughout the concrete, contractors only add the ornamental pieces to a topmost cement layer that sits over a bare concrete slab. Because the aggregates fill up the upper portion only — where they stick out and thus add decorative value — you'll need less overall, and you'll get more value out of the aggregates.
A third possible way for the contractors to embed decorative aggregates is by hand. After pouring the cement and before it's totally set, they arrange the pebbles or stones one by one, until they've created the design you asked for. This way, they have ultimate control to handpick which colours to place and what size.
Revealing the Aggregates
The next stage involves removing the top mortar to reveal the decorative embellishments. This can be done only using water and a broom until the stones stick out to the desired level. Timing is crucial as the stones need to sit firm within the cement and not be washed away, but the cement needs to be soft enough to remove. A retardant that slows the hardening process provides a broader time for the revealing process. Sandblasting a solidified surface provides a rougher option, but this technique can dull and damage the aggregates at the same time.