What is Aggregate Sealer?

An aggregate sealer is a protective finish used on certain types of concrete paving. It may consist of silicone, resins, or even linseed oil, depending on the product. Standard concrete typically features a smooth, uniform surface, with all gravel and aggregate materials hidden from view. Some users prefer the look of exposed aggregate, which gives the concrete a roughly textured surface. Just as concrete sealers protect standard concrete, an aggregate sealer can protect exposed aggregate.

The concrete used in exposed aggregate paving is typically very soft, which results in heavy wear over time. An aggregate sealer can slow this wear and extend the life of the surface. It also protects the concrete and aggregate materials from dirt buildup, and helps maintain a clean, attractive finish.

Aggregate sealer comes in two basic varieties, with each offering its own benefits and drawbacks. Wet-look aggregate sealer forms a transparent film over the surface of the concrete. It offers a high level of protection against moisture and stains, but may darken the overall appearance of the aggregate surface. This type of sealer provides a glossy, attractive finish, but may be slippery. Wet-look sealers tend to be the most affordable product for aggregate sealing.

Penetrating sealers do not form a protective film over the aggregate surface. Instead, they soak into the concrete to protect from the inside out. These sealers provide the highest level of moisture protection, but also tend to be the more expensive of the two. They are less stain resistant than wet-look sealers, and can only be applied over clean, unsealed concrete.

For most users, the key to successful sealing is in balancing gloss and traction. Though many users prefer the appearance of a high-gloss surface, glossy finishes are often slippery and dangerous, especially when wet. Some installers may add sand or other gritty materials to increase traction, while others may stick with penetrating sealers to maximize safety.

When choosing an aggregate sealer, buyers should look for environmentally-friendly products labeled "Low-VOC." This means that the product is free of volatile organic compounds, which pose a threat to health and the earth. It's also important to look for products with built-in UV protection. This prevents yellowing or discoloration after years of sun exposure.

Many aggregate sealers are fairly simple to apply, and require only basic tools. Prior to application, the concrete should be cleaned to remove any existing seal coats. Next, the sealer can be applied using a standard paint roller or brush. A second coat is often required to ensure adequate protection. All aggregate sealers should be allowed to dry completely prior to any foot traffic entering the area.