Let's face it -- a concrete driveway is a very practical and durable installation, but it's hardly a thing of beauty. Your average concrete driveway can look especially drab if your neighbours sport more attractive gravel or stone-paved driveways.
However, a concrete driveway can become a genuinely attractive piece of architecture if you choose the right concrete for the job. One of the most popular ways of jazzing up a concrete driveway is by exposing its aggregate by removing the top layer of mortar until the stones and aggregates contained within are exposed, creating a distinctive, naturalistic look that can set your driveway apart for all of its neighbours. However, there are several methods used to expose concrete aggregate and achieve this look, and you should decide which one is best for your needs before undertaking any exposed aggregate project.
Washing and brushing
This simple method of exposing your drvieway's aggregate has been in use for many years but is no less effective for its age. By simply blasting the surface of your driveway with pressurised water before scrubbing it with a stiff-bristled broom, you can steadily eat away at the mortar on the surface of your driveway until the attractive stones and aggregates contained within the concrete are exposed.
This method requires no specialised equipment, is extremely environmentally friendly, and is simple enough for the dedicated DIYer to take on themselves. However, washing and brushing is a very laborious and time consuming process, especially if you have a large driveway servicing multiple cars. Hiring professional concrete experts to take on the task will make the work much quicker and easier, but can be expensive if many hours of labour are required.
This aggregate exposure method is decidedly less subtle, and involves the used of sandblasters and shotblasters to quickly and effectively remove the top layer of your concrete driveway. This approach can be very time and cost-efficient, and is particularly well suited for exposing the aggregate of larger concrete driveways. It can also be performed on a concrete driveway months or even years after it was originally laid, giving you a great degree of flexibility if you decide you want a change of look in the future.
Unfortunately, abrasive blasting is also very loud and disturbing, and should not be attempted without the assistance of trained professionals. Shotblasters in particular can be very dangerous pieces of equipment in inexperienced hands. This harsh exposure method also deals a small but significant amount of damage to the structural integrity of the concrete, and may cause your concrete to degrade and crumble more quickly as it ages.
Surface retarders are specialised liquid compounds which are sprayed onto the surface of your driveway immediately after it is first laid. These compounds prevent the surface of the concrete from setting solid, and allow it to be removed very quickly and easily to expose the aggregate hidden beneath.
This method is used by most professional concrete contractors, and is very simple and inexpensive. The un-set mortar can be removed with pressure washers or simple brushing, and the retarding compound can remain effective for several days if bad weather or unforeseen circumstances should delay the exposure process. However, if the concrete is allowed to fully set and cure, the surface retarder becomes ineffective and you will have to turn to washing and brushing or abrasive blasting to achieve the desired results.