Exposed aggregate refers to a substance that is added to concrete but which is purposely meant to be exposed, either to add color and visual appeal or to provide traction in the form of a bumpy texture, or both. If you're having concrete poured on your home's driveway, walkway, patio or another space, note a few tips for choosing the best exposed aggregate.
1. Avoid iron
When choosing any exposed aggregate, avoid iron or any type of iron mixture. Iron can stain concrete and cause it to discolor over time. If your contractor offers any type of iron product, you might ask how they can ensure your concrete will avoid staining, as this might involve a special type of sealant over the aggregate.
Rounded aggregates can provide an easier walking surface, so these can be good for a walkway or patio. However, they may not provide the best traction when the surface is wet so they may not be the right choice for a driveway. For traction on any surface, choose a bumpier aggregate or one with a lot of variety in the shape. Avoid flat aggregates as these can easily become dislodged, leaving you with holes or indentations in the concrete.
Note too that larger aggregates also provide more texture and traction. For driveways, opt for something larger in shape, but for a patio where you might want to put down furniture without it becoming uneven and "wobbly," choose a smaller shape and size aggregate.
3. Recycled materials
If you're very eco-conscious, you might choose a recycled material for your exposed aggregate. This is often colored glass that has been taken from other projects and then broken down, dyed and buffed. This material reflects light very well and can create a colorful area for walkways and patios, and it keeps the glass out of landfills. It also reduces the need to harvest virgin materials for your aggregate.
All concrete needs regular sealing to keep it intact and in good repair, and an exposed aggregate surface is no different. Discuss your options with a manufacturer and note how it needs to be maintained; some aggregates may need more sealing than others, or they may need special sealants that can be more costly. You'll want to take into account the cost and work involved in maintaining your exposed aggregate through the years, so be sure you ask about this when making your choice.