We field a lot of questions from home and business owners weighing up a new surface. Here are plain answers to the ones we hear most often. If yours is not covered, just ask us.
What is bitumen?
Bitumen is a thick, sticky, black substance that comes from refining petroleum. It is the binder that holds a road surface together, and it has excellent waterproofing and adhesive properties. Sprayed onto a prepared base and covered with aggregate, it forms a spray seal that can carry heavy loads in the right conditions.
What is asphalt?
Asphalt is a pre-mixed composite of aggregate and a bitumen binder, produced at a plant and laid hot. In Australia the two words mean different things, even though in some countries they are used interchangeably. Put simply, bitumen is the glue; asphalt is the finished mix that glue holds together.
Is there really a difference between the two?
Yes. Bitumen is the liquid binder. Asphalt is aggregate combined with that binder into a solid surface. A bitumen spray seal is built up in layers on site, while asphalt arrives ready-mixed and is rolled out for a smoother, denser finish.
What about tarmac, is that the same as asphalt?
No, and tarmac is rarely used in Australia now. Both use gravel and sand, but tarmac is bound with tar, which softens and wears far faster under our sun. Asphalt uses a bitumen binder that holds up much better to heat and traffic.
What is hot mix asphalt?
Hot mix asphalt is aggregate and bitumen blended and laid at high temperature so it compacts to a strong, dense surface. It is the workhorse for high-traffic areas, roads, driveways and car parks. Our hot mix asphalt page has more detail.
What is a two-coat seal?
A two-coat seal lays a first pass of larger aggregate on a bitumen binder, then a second pass of smaller aggregate on more binder. The two sizes interlock, which makes the surface more durable and more resistant to stone loss than a single seal.
Still have a question?
There is a lot that goes into surfacing, and every site is different. We work with residential, commercial and industrial customers across Brisbane, the Gold Coast, Ipswich, the Sunshine Coast and Toowoomba.
If you did not find your answer here, get in touch and one of our team will talk it through and give you a free quote.