Asphalt Sealcoating: Adding an Aggregate

Like any object that is exposed to the ravages of weather, asphalt pavement can become faded, dry or brittle. However, your pavement must also bear the weight of traffic. The heavier or more numerous the vehicles are that are using your pavement, the more likely it is that your pavement can be damaged. Sealcoating is a highly effective, economical way to protect your pavement from both the weather and the traffic it must bear. However, for sealcoating to be effective and long-lasting, the sealant mix must be prepared properly. A good mix will include an aggregate.

Asphalt Sealcoating: Adding an Aggregate

In general, aggregates are particulates that are added to a liquid or slurry. One example of a commonly seen aggregate would be the gravel or small rocks incorporated into a concrete mix. For sealcoating mixes, the aggregate of choice is silica sand.

• Silica sand is essentially quartz that has been pulverized by wave action occurring along coastlines.
• It is extremely pure, requiring little additional cleaning before it can be used in sealcoating.
• The tiny grains tend to be of a uniform size, eliminating the need to process the sand through a crusher.
• Silica sand is plentiful and concentrated in areas where it is easy to collect, so it is an economical aggregate for sealcoating mixes.

Why Do Sealant Mixes Need an Aggregate?

Adding an aggregate to a sealcoating mix offers several immediate and long-term benefits.

• Aggregates improve surface traction. Without an aggregate, the sealed surface can be slippery, especially during or immediately after it rains. Sand added to a sealant mix helps prevent tire slippage, but it also improves traction for pedestrians.
• Aggregates improve the sealant’s durability. An aggregate helps the sealant establish a stronger bond with the pavement, so the sealcoating is less likely to be dislodged by vehicles that are braking or turning. A sealant containing an aggregate is also tougher, so it will last longer under normal conditions than a sealant without an aggregate.
• The surface will be more visually appealing. The sand in the sealcoating mix will settle into any hairline cracks or minor voids, giving the surface a smoother, cleaner appearance.
• Aggregates help control the drying of the sealant. There will be less water in the mix, so evaporation will not take as long. However, aggregates also help prevent the water from evaporating too quickly; this can lead to cracks on the surface of the sealant.

Why Do Some Contractors Omit an Aggregate?

The decision to leave out an aggregate is typically based on the contractor’s finances. A quality machine that can keep the mix agitated and the aggregate distributed evenly costs in the neighborhood of $25,000. Furthermore, although silica sand is economical, it is not free, so paying for the aggregate reduces the contractor’s profit. In addition, without an aggregate, the contractor can add more water, so a gallon of the mix can be sprayed on a larger area.

A credible asphalt company who wants your continued business will always add an aggregate. The people who do not incorporate an aggregate tend to be gypsy contractors who are constantly moving from town to town; they can afford neither the cost nor the encumbrance of quality equipment. They often prepare their mixes in a large barrel or recycled drum. However, since there is no agitator or pump, it is immaterial whether an aggregate is used — it would quickly fall out of suspension and do little more than coat the bottom of the container.

Hire a True Sealcoating Professional

All Pro Asphalt is a highly respected asphalt maintenance company serving commercial and residential customers throughout the greater Kansas City area. We take pride in delivering quality work that goes beyond the customer’s expectations. In addition to asphalt sealcoating, we also offer parking lot striping, asphalt crack sealing, asphalt paving, infrared asphalt restoration, asphalt repair and concrete work. You can call (816) 249-6800 or submit our online form to request a free quote.

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