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Tacks, Seals & Benefits: Understanding Asphalt Emulsions And Why Your Pavement Needs It

Emulsions are a scarcely covered subject in asphalt paving because they are too complex to explain, and everyone takes a scientific approach to describe them. The simplest explanation is, emulsions make the asphalt binder less fudgy and more grippy in colder temperatures, so the asphalt binds better with the tar, forming a suitable pavement.

Asphalt emulsions are made from water, asphalt, and an emulsifying ingredient that is usually soap. These ingredients do not mix in nature, but through mixing machines, they can exist as a mixture temporarily. The mixed ingredients’ machines are designed to induce a uniform electrical charge on the asphalt particles suspended in the mix so they don’t clump together. That’s like magnets and opposing poles repelling each other. For application purposes, the mixture is kept warm and continually churned.

Purpose of Asphalt Emulsions:

An emulsion is designed to break down when it is sprayed onto the freshly laid pavement. The water and the asphalt separate. The water evaporates, and the asphalt is left behind as a strong pavement adhesive that acts as a surface sealant and protective coat. The emulsion also keeps the asphalt aggregates together in colder temperatures, unlike conventional tar and bitumen binder, which does not cling well to chips. There are bitumen-based and polymer-based emulsions for better elastic recovery of pavement from heavy vehicles, plus self-maintenance in hotter months of the asphalt structure.


Emulsions have a range of applications in both asphalt and concrete pavement. Their viscosity makes them ideal for maintenance and repair purposes. There are many emulsion mixes, each with specific functions for protection, recycling, adhesion, reclaiming, stabilizing, and sealing asphalt. Emulsions are also used as layer binders in asphalt paving. Imagine a triple cheeseburger with multiple layers of cheesy binding, keeping the sandwiched contents secured inside.

When a pavement, driveway, or parking lot is freshly paved, the first thing is a prime coat of thin consistency emulsion, and then a tack coat is applied, which is a thicker viscosity designed to hold the chips in place. Next, either a seal coat can be applied, or more emulsion, in the required number of coats to protect the surface against water intrusion or weathering by vehicle use. Emulsions can be used on concrete pavement, though polymer-based ones are preferred for a smoother finish.

Benefits of Asphalt Emulsions:

  1. Emulsions are an environmentally-friendly innovation with a low carbon footprint and safe usage.
  2. They are easily stored, mixed, diluted, and preparable for application by a spray nozzle that electrically charges micro-droplets of asphalt to a negative charge.
  3. Emulsions can be applied at temperatures as low as 55 degrees Fahrenheit with just slight warming and stay viscous even then to cling to chips better.
  4. Emulsions can be sprayed during wet weather without changing their efficacy as a binder and protective coat.
  5. When used as surface coats, emulsions possess the anti-stripping ability, meaning painted signage does not wear off fast on these surfaces.
  6. You may be amazed to know that emulsions stabilize sandy soils in the desert regions in the US for road construction.

We hope that this cleared any confusions you may have had between emulsions, tack coats, prime coats, and seal coats. At Surface Solutions, this is precisely the knowledge you should expect us to be well versed in. We provide a range of seal coating and paving solutions across Ocean City, MD, so you’re most welcome to get your free quotes on any surfacing solutions you may require.

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