Common Questions Answered

Common Questions Answered - Road Sealing with Road Seal Australia

The top frequently asked questions about road sealing services and information answered for you!

We’ve rounded up the queries we’ve received over time from curious residential and commercial property owners and given them our best answers. Here are some of the most frequently asked questions about bitumen, asphalt, and other pavement processes.


What is bitumen?

Bitumen is a sticky, viscous liquid formed as a residue of petroleum distillation. It is sprayed on the road and covered with an aggregate. Bitumen is a standard binder for aggregate. The combination of bitumen, sand and aggregate forms what is called asphalt in Australia.

Bitumen has many waterproofing, sealing, and adhesive properties that allow for better binding. It comes from complex hydrocarbons, mostly containing carbon, iron, sulphur, and oxygen.

A good bitumen seal can handle heavy loads in the right temperature. It can deform only on extreme loads, making it perfect for roadwork, parking lots, and driveways.


What is asphalt?

Asphalt is a road material that uses aggregate and a binder to create a composite material you can use for roadwork. In America, asphalt has the same meaning as bitumen. In Australia, bitumen and asphalt are two different things.

Asphalt is always aggregate mixed with bitumen. There are several ways to make the aggregate-binder mix, such as hot-mixing, warm-mixing, cold-mixing, cut-back, and mastic asphalt.

Is there a difference between asphalt and bitumen?

Yes, bitumen and asphalt are two different substances that have two separate processes. Bitumen is the substance that seals asphalt and holds it together, acting as a liquid binder. It is common for most people to interchange bitumen and asphalt.

Bitumen seal works by spraying a layer of bitumen and covering it with aggregate. Road work repeats this to make a double-coat seal.

In some cases, bitumen is a substitute for common asphalt, which we call “mixture asphalt.” Bitumen mixtures use bitumen, stones, sand, or gravel.

Advantages of using bitumen

What are the advantages of using bitumen?

Using a bitumen seal has its advantages. If you’re looking to pave a driveway for home or commercial use, it’s best to use a bitumen spray seal.

Bitumen is fairly cheap compared to standard asphalt that uses other binders. You can also recycle it for use in the future. 

Bitumen sealing also protects your paving from small cracks. Your driveway will wear from use, the elements, and typical weathering. By sealing it, you improve its lifespan and give it a smoother finish for a more comfortable drive.

What is the difference between asphalt and tarmac?

Another misconception is that asphalt driveways and tarmac are the same. Tarmac is no longer used in Australia, mostly because of its many downsides. Asphalt driveways are more common because it’s easy to produce and lasts far longer than tarmac.

Asphalt and tarmac are similar in their basic composition. Both use gravel and sand as an aggregate, but the difference comes in their binding agent. Tarmac uses tar as a binder and coating, while asphalt uses other materials like bitumen.

Tarmacs are less durable and melt under the Australian sun. It’s common for tarmac to wear down faster than asphalt. Asphalt materials, on the other hand, are hardier under pressure and need super high temperatures to start melting.

Hot mix asphalt

What is hot mix asphalt?

Hot mix asphalt is the combination of 95% stone, sand, and/or gravel bound together by bitumen. While this is similar to common asphalt, the difference lies in the process of producing this sort of asphalt.

In hot-mixing, the aggregate receives uniform mixing and coating, heating the bitumen seal to decrease its viscosity. The aggregate then undergoes drying to remove the moisture to increase its durability.

The mixing will generally go between 95 and 166 degrees Celsius, depending on the binder you’re using. Paving and compaction will then start while the mixture is hot so that it creates the desired density.

Why is hot mix asphalt better than other processes?

Hot mix asphalt paving mixtures can create different types of aggregate combinations. Each combination has characteristics of which construction workers and civil engineers can take advantage.

The most common value that infrastructure services love with hot mix asphalt is its durability and flexibility. Depending on where you use it, you can pack it to a density that gives you financial flexibility.

Hot mix asphalt is common in high-traffic pavements like roads, driveways, parking lots, racetracks, and even airfields. If you’re looking to use it for a private service road that wouldn’t get heaps of traffic, you can pack it with less density to save you some expense.

For maintenance purposes, you can also use HMA Ultra-Thin, which adds hot mix asphalt for thin lift placement. By adding it on top of an already existing pavement, you can improve your roads that are already suffering from aging, oxidation, and surface disintegration.

Resin asphalt

What is resin asphalt?

Resin asphalt is a type of aggregate mixture that works much differently than bitumen asphalt. This type of asphalt is a mixture of aggregate stones of similar sizes without sand or other materials. A high-quality clear resin becomes the binding agent for this type of surface.

Resin asphalt is hard, flexible, and firm. As the resin acts as a clear glue, it creates a rough surface that shows off the beauty of the aggregate used. Its general use is in walkways, footpaths, and driveways where decorative value is crucial.

Resin asphalt is usable both indoors and outdoors. It is usable on any scale and type of project to help suit the budget of the client. It is usable for bus lanes, patios, road junctions, commercial properties, and even car parks.

What are the advantages of using resin asphalt?

Some advantages of resin asphalt include its durability, flexibility, and ability to be decorated. Resin asphalt experts may also add different colours using special resins and a variety of coloured aggregates. For residential uses, blending aggregates can create appealing colour schemes.

A resin asphalt is not as frequently used compared to common hot mix asphalt, mainly because of resin asphalt’s cost. Until recently, resin asphalt was much more expensive due to the logistics of producing and using it. The aggregate needs to have almost the same particle size to prevent extreme roughness and surface noise.

Another major barrier to its utilisation is customer awareness. Resin surfaces are not widespread, and many offer it at a much higher cost due to its decorative value. Nonetheless, those who understand its use know how effective and reliable it is for various projects.

Two coat seal

What is a two coat seal?

A two-coat seal is an aggregate laying technique that uses two types of asphalt mix. The first aggregate uses large-sized aggregate with bitumen with a secondary layer of smaller aggregate sealed over.

The interlocking combination of a two-coat seal allows for a longer-lasting surface. By allowing interlock between larger and smaller aggregate, the surface is more resistant to stripping. 

A two-coat seal starts with a large base and a prime seal. The first binder application goes in, with the first, larger aggregate coming after. The second binder goes on top together with the second, smaller aggregate to create a double/double seal.

Did you find the answers you’re looking for? We know there’s a lot that goes into what we do, so if you cannot find the answer above, feel free to contact us to speak with one of our friendly team members today.