There are lots of options to choose from when considering which type of pavement surface is right for your job. Two of the most traditional types, chip seal and asphalt, offer similar, smooth surfaces, with a variety of different finish options.
Chipseal – What is Chipseal?
Chip seals are constructed by evenly distributing a thin base of hot bitumen (a by-product of crude oil) onto an existing pavement or prepared road base area and then embedding finely graded aggregate into it. The aggregate is evenly distributed over the hot seal spray, then rolled into the bitumen using heavy rubber tyred rollers creating a paved surface. A chip-seal-surfaced pavement can optionally be sealed with a top layer, which is referred to as a two coat seal.
- Chipseal is the original paving style. If you’ve spent any time driving over old country roads, you might already be familiar with its look.
- Chipseal will need to be reapplied about every 5 to 8 years depending on the area used.
- A base layer of hot liquid bitumen is applied to the prepared surface, usually sprayed and then stone is applied and rolled into the bitumen. This is usually done twice and called a two coat chip seal. Normally, a 10mm pre-coated stone is applied first, then the stone is rolled and the process is repeated and then a 7mm stone is applied and rolled.
- The embedded stones can also provide excellent traction on slopes and high moisture areas. Chip seal is commonly used in rural areas for its natural look and is a lot cheaper than asphalt but unfortunately not as durable.
- Chip seal is not recommended where there is high turning of vehicles, especially heavy vehicles.
Asphalt – What is Asphalt?
Asphalt is also a hot product, consisting of bitumen, but is mixed at a batching plant together with aggregates (chips) of sand and dust at a high temperature. Asphalt comes out of the plant at 180 degrees Celsius and is laid by either hand or with a paving machine.
Asphalt needs to be laid at a minimum of 25mm deep (driveway or carpark), and can be laid up to 100mm in one layer, (typically used as a structural layer). Once it’s laid, it is compacted with a suitable motorised roller. If it’s only a small patch a motorised plate compactor can be used.
Asphalt needs to be laid reasonably quickly because if it cools below its critical temperature it won’t compact as well. Asphalt is a lot stronger and smoother than chipseal.
- Asphalt surfaces provide an almost unlimited variety in form and flexibility and can last as long as 25 years, offering excellent long-term value. Its flexibility makes it perfect for areas that would not be appropriate for concrete or other surfaces such as steep incline areas.
- The look is smooth and modern. The benefits of asphalt include trip free surfaces, reduced dust, and excellent waterproofing properties.
- Asphalt should last up to and even beyond 15 years, depending on application.
- Unlike chip seal, asphalt does tend to get very hot in summer due to the heat-absorbing properties of the dark pavement colour.
- Asphalt surfaces work well in both residential and commercial applications. It is appropriate for new construction, remodelling and patching of existing surfaces.
- Asphalt can be laid and used in heavy vehicle areas, where turning and heavy vehicle movement is paramount. For example, a loading dock or hard stand. A chip seal surface won’t stand up to this.
So, there you have it, I hope this explanation helps. If you would like to know more, please contact us.