Exploring The Feasibility: Can You Put Asphalt Sealer Over Concrete Surfaces?

What Are The Differences Between Asphalt and Concrete?

While both asphalt and concrete are made from aggregates (sand, gravel, or crushed stone), and have a binder, the main difference lies in the type of binder used. Asphalt uses a petroleum-based binder (bitumen) which is a sticky substance derived from crude oil, while concrete uses a cement-based binder, which is a powdery substance made from limestone and clay. The difference in these binders is what gives asphalt and concrete their performance, durability, and overall properties, and is what makes them incompatible with one another. For example:

• Asphalt is flexible, resilient, and can expand and contract with temperature changes. Concrete is rigid, durable, and can withstand high compressive forces.
• Asphalt allows water to seep through its surface (porous). Concrete blocks water from penetrating its surface (impervious).
• Asphalt is dark in color, which absorbs heat and melts snow and ice faster. Concrete is light in color, which reflects heat and allows it to stay cooler

These differences in composition result in contrasting properties, and is why concrete requires different sealant treatments.

What Is The Purpose and Composition of Asphalt Sealer?

Asphalt sealer is a protective coating that is applied over asphalt pavement to extend its lifespan and improve its appearance. It consists of refined coal tar (asphalt emulsion), water, sand, clay, polymers, and additives, and works by filling in the pores/cracks present in the asphalt’s surface. The sealant’s smooth and uniform layer prevents water, oil, and chemical contaminants from penetrating the surface, and blocks UV rays so that the bitumen binder doesn’t become oxidized and degrade.

The Incompatibility With Concrete

So, can you put asphalt sealer over concrete? No, the sealer is incompatible with the concrete’s surface texture and lack of porosity.

1. Asphalt sealer is not compatible with the cement binder in the concrete. The chemical reaction between the two materials can cause the sealer to peel off.

2. Asphalt sealer isn’t designed to adhere to a smooth and hard surface. The sealer won’t penetrate the concrete’s surface or form a strong bond, leading to premature failure.

3. Asphalt sealer is not suitable for the thermal properties of concrete. The sealer won’t expand and contract with the concrete surface, hindering the concrete’s ability to move. This can lead to delamination, and a compromised appearance.