Create a Beautiful, Natural Look with Exposed Aggregate

What Is Exposed Aggregate?

Exposed aggregate is created by using an application of a chemical retarder to reveal the aggregate beneath the surface of concrete. A unique, colourful texture is exposed that personalizes your drive, patio, or walkway. Patterned Concrete® Niagara installs exposed aggregate in a variety of ways including the simple exposed aggregate by itself or with both Patterned Concrete® and natural stones.

The Technique

In order to create the exposed aggregate, the application of the retarder prevents the matrix (often the concrete) from fully hardening at the surface. The concrete is allowed to cure overnight and then the unhardened layer at the surface is then removed by high pressure water washing. This exposes the aggregate used in the concrete, creating unique textures and patterns.

Positive Features

1. No damage or change to the aggregate by the cleaning method

2. Minor imperfections do not affect the final product

3. Easy-to-patch finish

4. Water runoff distributed more evenly, reducing streaks on the surface

5. The variation in colour choices is endless


1. Variations in the exposure are not easy to correct

2. Vertical, radius, or complicated surfaces are harder to cast uniformly

3. Water washing is seasonally restricted in Northern climates


1. Finish displays aggregate in its natural beauty

2. Control of mix, slump, retarder, and the time of exposure is important in the water-washing method. Having as little contrast between matrix and aggregate minimizes possible issues in the aggregate.

If the bright, natural colours of the aggregate are the prime concern, water washing is the best way to achieve this result. Call Patterned Concrete® Niagara today for details.

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