What is Asphalt Sealcoating Made Of?

Whether your asphalt pavement is new or old, it’s susceptible to cracks and potholes. Moreover, your newly paved driveway can fade, this giving it an old and dull appearance a few months after the installation. However, you can prevent such damages by sealcoating your pavement as required. 

An asphalt sealer gives your asphalt pavement the protective layer it requires to withstand the effects of external elements like UV rays, water, ice, as well as gas, oil, and chemical spills. Besides, sealcoating your asphalt pavement restores its rich, black appearance while preventing the surface from becoming slippery. 

The following are the 4 ingredients of an asphalt sealcoat

There are two types of asphalt sealers: asphalt emulsion and coal-tar-based sealers. Later in this post, we shall look at the ingredients of these two sealers. But first, we shall look at the general ingredients of an asphalt sealer. 

• Binding agent – the binding agent or binder is the major ingredient of an asphalt sealcoat, which binds together the other ingredients. Also, the binding agent gives the asphalt surface the required protection, its rich dark color, and binds the sealant to the surface. 

• Aggregates – these include clay, fillers, and sand, which give the sealcoat the required tensile strength, toughness, and dimensional strength. Moreover, the aggregates reduce the rigidity of the pavement, thus giving it the flexibility it needs, particularly during extremely hot temperatures.

• Additives – different asphalt sealers have different additives, which serve different purposes. The main reason to add these additives to asphalt sealcoat is to improve water repellency, reduce the curing time, change the sand suspension, improve flexibility, and add resistance to salts and other petroleum products. 

• Water – one might ask, what’s the need for water in a petroleum-based product. Well, water helps to spread all the other ingredients. Besides, it helps to retain the fluidity of the sealcoat, in addition to making it easier to store, handle, and apply. 

Because you have an idea of what an asphalt sealcoat is made of, we shall look at two common types of asphalt sealers and their ingredients. 

Asphalt-based sealer

Also known as ABS, asphalt-based-sealers are made of crude oil, and they constitute around 50 – 70% of a typical asphalt emulsion. Unlike coal tar based-sealers, asphalt-based sealers have different viscosity and unique viscosity—thanks to the different production techniques of crude oil refineries. Since asphalt is a by-product of petroleum refinery, asphalt-based sealers don’t repel fuels. This is one of the most significant drawbacks of using asphalt-based sealers on your sealcoating project.  

The following are the two additional ingredients of asphalt-based sealers:

• Emulsifiers – the emulsifying agents used in asphalt-based sealers help make it strong and more durable. But, unlike coal tar-based sealers, the emulsifiers used in asphalt-based sealers can differ based on the chemical composition and properties of the asphalt used. Besides, the emulsifying agents are not standardized as with coal tar-based sealers. Therefore, the emulsifiers are primarily used for chemical compatibility, which helps to strengthen the sealer. 
• Additives – the two common additives used in asphalt-based sealers are polymer and non-polymer additives, including waterborne acrylic or waterborne vinyl resin. The temperature of your locality and the traffic volume is the key determinants of the additives used in your sealant. However, it’s important to observe extreme caution when adding additives to your sealant since asphalt based-sealers aren’t standardized, meaning they might contain a chemical incompatible with your additives. For example, you can’t mix asphalt-based sealers containing anionic emulsifiers with a cationic polymer emulsion. This can make the emulsifiers thicker, affecting the overall effectiveness of the sealer. 

Coal tar-based sealers

Coal tar is a by-product of gasification, liquefaction, or coal coking. The residue that remains after distilling coal tar is known as coal-tar pitch—this is the black liquid that remains after removing different oils from coal tar. After that, the coal tar pitch is refined into 12 different viscosity grades. RT-12 is the most viscous grade, and it’s the main ingredient of coal tar-based sealers. 

The following are the two additional ingredients of coal tar-based sealers

• Emulsifying agent – the emulsifying agent used in coal tar-based sealers is a water-soluble, soap-like product. It has an ionic head and hydrocarbon tail, which give the sealer the electric charge it needs for these two components to resist each other and to remain suspended in water. 
• Additives – the additives in a coal tar-based asphalt sealer include sand, clay, and polymer. These make it easier to apply the sealant and improve its durability. Because coal tar-based asphalt sealers must meet specified federal standards during production, the additives allow the professionals to achieve different results. 

According to the experts from CSG Sealcoating, Orlando, after applying a coal tar-based sealer, the emulsifier destabilizes, making the particles in the sealer bond and creating a solid protective layer. 

Bottom Line

There you go! These are the two common types of asphalt sealers and their ingredients. Note that each of these sealers has its pros and cons, and it’s essential to consult with your sealcoating contractor to determine the suitable sealer for your property.