Short answer
Exposed aggregate concrete is poured concrete whose top layer is removed after placing so the stones in the mix show on the surface. It has a natural, textured look and good traction, and it costs more than a broom finish. Like any exterior concrete in Ontario, it needs an air-entrained mix, a solid base and sealing.
How exposed aggregate is made
The slab is poured and finished like any other, but instead of a broom texture, the cement paste on the surface is removed to reveal the stones. This is commonly done by applying a surface retarder and washing or brushing off the top layer once the slab has set enough, or by a light abrasive process after curing.
The stones, called aggregate, can be selected for colour: river rock, granite chips, limestone or blends. The cement colour can also be tinted, so the finished surface combines both.
- Base, forms and reinforcement are prepared as for any slab.
- Concrete with the chosen aggregate is placed and levelled.
- A retarder is applied or the surface is timed for washing.
- The surface paste is washed or brushed away to the desired depth.
- The slab is cured, then sealed to protect the finish and enhance colour.
Where it works well
- Driveways. A popular upgrade because the texture hides small stains and tyre marks.
- Walkways and entries. Good traction in wet conditions.
- Pool decks and patios. Cooler underfoot than smooth concrete and less slippery when wet.
- Steps. Only with care: a contractor should explain how edges and nosings will be finished.
It is less suited to areas that need frequent snow shovelling with metal blades, where the stones can catch and loosen over time. Plastic shovels and gentler snow clearing help protect the surface.
Aggregate versus other finishes
| Feature | Exposed aggregate | Broom finish | Stamped |
|---|---|---|---|
| Look | Natural stone texture | Plain ridged grey | Pattern and colour |
| Traction | Very good | Good | Fair to good |
| Hides stains | Well | Moderately | Depends on sealer |
| Relative cost | Medium to higher | Lowest | Higher |
| Repair | Patches can look different | Easy to blend | Hard to match pattern |
See stamped concrete and the finishes comparison for more detail.
Winter performance and sealing
Exposed aggregate has a more open surface than broom-finished concrete, so it absorbs more water if left unsealed. Over time, freeze-thaw and de-icing salt can loosen stones and scale the paste around them. The usual protections apply: air-entrained concrete, a sound base with good drainage and a quality penetrating or film-forming sealer, renewed on a schedule recommended by your contractor.
Read the salt and frost damage guide for more detail on what causes scaling and how to reduce it.
Cost and what to ask a contractor
There is no separate published Ontario price for exposed aggregate in the sources we reviewed, so it is best treated as a premium over a plain slab. The same Ontario price guide used elsewhere on this site (HomeStars, August 2026, Ottawa-based) lists basic slabs at about $3.80 to $5 per square foot and decorative work higher, but those ranges are estimates and not a London quote. Ask for a line-by-line written quote.
- Which aggregate will be used and can I see a sample board?
- How deep will the surface be exposed?
- Which sealer will be used and how often should it be renewed?
- Is the concrete air-entrained for exterior exposure?
- Do you carry liability insurance and a current WSIB clearance certificate?
For a general breakdown, see the concrete cost guide.
Frequently asked questions
Is exposed aggregate more expensive than regular concrete?
Generally yes. The extra labour and materials mean it costs more than a broom finish, though prices vary by contractor and design. Ask for a written quote that shows the finish as a separate line.
Is exposed aggregate slippery?
No. The stone texture gives good traction, which is one reason it is used around pools and on driveways.
Can I shovel snow from exposed aggregate?
Yes, but use a plastic blade and avoid aggressive scraping, which can loosen stones over time.
Does exposed aggregate need to be sealed?
Most contractors recommend it. A sealer reduces water and salt absorption and can deepen the colour of the stones.
Can exposed aggregate be repaired?
Small repairs are possible, but matching the stones and colour can be difficult, so patches may be visible. See concrete repair.
Is exposed aggregate good for driveways in Ontario?
It can be, if the concrete is air-entrained, the base is sound and the surface is sealed. Without those, any concrete finish can fail early.