Exposed aggregate concrete is a style of decorative concrete where the aggregates of the cement, mainly pebbles and small stones, are exposed in contrast to the traditional smooth finish of concrete surfaces. Exposed aggregate concrete adds visual interest to a surface because of its random designs and diverse colors.
It is a cost-effective way to give old or new concrete an appealing look. Aside from looks and a reasonable price, exposed aggregate also features the main characteristic of concrete – strength. All these make this option widely popular. Because it’s very hard wearing, some common applications of exposed aggregate concrete are public areas including footpaths and traffic areas such as driveways, sidewalks, patios, plazas or pool decks. It can also be used on vertical applications such as decorative walls and building facades.
Aside from the fact that it is durable against heavy traffic and oftentimes cheaper than other decorative concrete techniques, here are more reasons why exposed aggregate concrete is popular:
- It has practically limitless texture and color options allowing a customized look. With the exception of sealing the finish and cleaning it occasionally, this option is very low maintenance.
- Its rugged surface poses less of a slipping hazard than brushed concrete.
- It is resistant to harsh climate conditions.
- Fewer tools or additional materials are needed in this method than other options.
- This method is easier to learn and master than other decorative concrete techniques.
- This technique has long been used since the early 20th century but it continues to be popular today with contractors discovering even more creative ways of using it. The two most common ways of achieving exposed aggregate concrete are:
1. Surface Dressing – In this method, decorative aggregate such as decorative stones, gravel, crushed glass, shells or quartzite is seeded onto freshly-placed cement. The cement must first be tapped about 5 to 9 mm below the required finish level before the aggregates are spread evenly over it and patted down the concrete surface. This method is ideal for smaller projects such as patios and garden footpaths.
2. Washed to Expose – The fresh concrete surface is washed away to expose the aggregates that are already part of the cement’s ingredients. Specifically, the cement’s fines are stripped away from the top 2 to 6 mm of the concrete surface to reveal the aggregates. This is the preferred method for commercial or heavy-duty applications.
In choosing a decorative aggregate, keep in mind that the type will determine the color palette of the finish and will also have an impact on the project’s overall cost. There are many reasonably-priced aggregates that will produce great results. Aside from color, hardness, shape, size and durability, consider locally-produced aggregates because they are readily available and, therefore, more economical.
Even more stunning effects can be achieved with exposed aggregate with the use of advanced techniques such as creating contrast by using different aggregates or alternating smooth surfaces with exposed aggregate finished areas. Some use strips of wood patterned stamped concrete as dividers to create accent. The possibilities when it comes to design are almost endless. What you can be certain of is that this decorative technique will offer you excellent value for your money.