How I Repaired My Concrete Driveway

Your Guide to Understanding Exposed Aggregate Concrete

In the concreting world, the term aggregate refers to particulate materials such as gravel, slag, recycled concrete, geo-synthetic aggregates and crushed stone. These materials often make up a large percentage of concrete mixes during construction. Therefore, it makes sense to consider having exposed aggregate concrete as your final finish. It is an affordable and creative way of finishing your concrete surface, and it is flexible enough for application in various places. You can use it on driveways, walkways, patios and interior spaces that need a rugged touch. Here is a guide that will teach you more about exposed aggregate concrete finishes:

How do you expose the aggregate?

Your exposed aggregate finish is ready for exposure after the concrete mixture has been laid. Your contractor can use different techniques to expose the underlying aggregate to deliver the finish you want. They take on this by exposing the top part of the aggregate while the rest of aggregate stays buried in the concrete for good. The techniques employed here include:

  • Brushing and washing – Brushing and washing is an old method used for exposed aggregate finishes. Here, the builders spray the area with a water jet and scrub lightly with a broom. The action removes the thin layer of surface mortar. Timing is critical to avoid overexposing the aggregate.
  • Abrasive blasting – Abrasive blasting is applicable for concrete surfaces that have settled and hardened. The contractor can use shot blasting or sand blasting to expose the aggregate. On the downside, abrasive blasting can fracture your concrete surface and dent the appearance. You are better off going for the exposed finish when the concrete is fresh.

How do you get it right when sealing?

Sealing an exposed aggregate concrete surface is critical for ensuring its durability and functional efficiency. Sealants are not mandatory, but they will reduce the maintenance costs for the exposed surface. When you're looking for a sealant, choose one with non-yellowing additives and excellent UV resistance. The seal should also allow recoating and repel water, stains and grease. If you want to seal a fresh aggregate surface, make sure that the surface is free of paste residue from cement. Do not seal the milky white paste.

How do you maintain your exposed aggregate?

Naturally, exposed aggregate surfaces are rugged and non-skid. They are designed to withstand heavy pedestrian and motoring traffic. Their tough nature calls for little maintenance. However, occasional cleaning and resealing will go a long way in maintaining the surface's structural integrity.