Boral Asphalt supplies high quality surfacing solutions for a wide range of road and other construction projects across Australia.
The Boral Asphalt business includes asphalt manufacturing sites, ‘spray seal’ depots, and an asphalt contracting service.
Clients often turn to Boral Australia for projects such as local road building and maintenance, through to highly complex major infrastructure programs including freeways, highways and airport runway resurfacing.
What is asphalt?
Asphalt is a durable, usually black-coloured material used for sealing and surfacing prepared areas. It is laid in place while hot, hardening as it cools to ambient temperature. Once hard, it provides a smooth but adhesive surface, making it suitable for road applications. Asphalt is sometimes incorrectly referred to as ‘bitumen’ or ‘tar’. Bitumen is, in fact, a key ingredient of asphalt - it is a sticky black or brown by-product of oil refining. Tar is derived from coal and is not used in the modern Australian asphalt manufacturing process.
How is asphalt made?
Asphalt is produced using a ‘fixed’ or ‘mobile’ plant. Quarry aggregate (crushed rock) and sand is combined in a rotating drum and dried at temperatures between 150 and 180 degrees Celsius to remove any moisture. ‘Fillers’ such as lime are then added before the mixture is coated with bitumen. The finished asphalt is then sent to either short-term storage, or loaded onto trucks for immediate delivery to our customers.
What are the uses of asphalt?
The primary use of our asphalt is to surface roads, highways and motorways across the country. Asphalt can, however, also be used for a variety of other works which require a smooth and durable surface. Examples of these works include car parks, commercial and domestic driveways, playing courts such as those used for netball, motor racing circuits and pedestrian accesses.
Where does the asphalt go after it is made?
Asphalt is a ‘perishable’ material. To remain usable, it has to be kept and laid at between 150 and 180 degrees Celsius. This means asphalt has a short ‘shelf life’ and so, in most cases, it is taken straight to where it is required as soon as it is made. This also means the asphalt needs to be produced just ahead of it being needed. As most roadworks now occur at night to avoid disrupting traffic, asphalt is often made outside of ‘normal’ business hours.
Who works at an asphalt plant?
Boral’s asphalt sites are managed by operators who oversee the largely automated production process. This automation allows the operators to set specific asphalt mixes in accordance with the requirements of each individual customer or project.
The operators also ensure each site’s obligations are being met with respect to planning and environmental obligations. They will additionally assist in the upkeep and maintenance of their site where their qualifications allow. Laboratory staff can also be found at asphalt sites. Their role is to test and ensure the quality and consistency of the asphalt products produced.
Transport drivers are attached to each site through our Logistics business. It’s their job to ensure the asphalt is transferred safely from the manufacturing location through to the relevant job site.
Does making asphalt have an effect on the surrounding environment?
Regardless of the type of operation, Boral’s company-wide aim is to do what we can to ensure our sites have the minimum influence upon those who live and work around us. All of our facilities are subject to a range of laws and regulations which govern the way they are allowed to operate.
The most prominent risks to this objective that we manage at our asphalt sites include excess noise, dust emissions and odours. A range of mitigations and practices have been developed at each location to address these and other factors. Our sites also have features to ensure any materials which could potentially affect the environment are safely stored and contained, and kept away from interacting with water flows.
Asphalt itself offers a limited risk to the environment given it hardens as it cools to ambient temperatures, meaning it cannot travel if spilt. It also cannot penetrate the ground more than a few centimetres.
Are asphalt plants noisy?
Generally, asphalt manufacture is no noisier than most other industrial processes. As with similar sites, each operation must comply with local and state limits applying to noise generation. To reduce noise levels, plants include mitigation measures such as cladding around potential noise sources. Practices such as ensuring aggregates are not poured into empty bins during night hours, and fitting low frequency reversing beepers to site vehicles, assist with noise reduction.
Sometimes the transport associated with asphalt sites can cause a disturbance, especially during night hours. To help avoid this, logistics are carefully planned to maximise the use of routes away from residential areas, and to give due consideration to the way the way Asphalt deliveries are scheduled.
How do you manage dust at an asphalt plant?
Asphalt plants are fitted with equipment designed to manage the dust which can be emitted during the production process, mainly from the aggregates used.
In modern plants, a ‘bag house’ is featured which, like a vacuum cleaner, captures dust before it is emitted to the open air. The dust can then be collected and returned to the production process for integration into further batches of asphalt. In older plants, water is used to ‘scrub’ the dust from the air.
On occasion, people tell us they can see dust being emitted from the stacks of our plants. These stacks in fact only emit steam as a result of the aggregate drying process – it’s been demonstrated that depending on your viewpoint and the location of the sun, the steam can be mistaken for dust.
‘Fugitive’ dust can also occur on the hard surfaces and roads of our plants. This is managed through the use of regular sweeping, with stockpiles monitored and watered in hotter, drier conditions to ensure they do not add to the level of fugitive dust at the site.
Why does asphalt smell?
Odours associated with asphalt are due to the use of bitumen in the production process. Bitumen contains a group of chemicals known as ‘aromatics’, as well as sulphides, which are highly odorous.
Reports of odour being noticeable outside our asphalt plants are usually linked to the loading and unloading of bitumen between tankers and storage tanks. To address this, we install activated carbon filters on the storage tanks to reduce the risk of odour escaping from them.
We can also adjust the asphalt mixing temperatures to as low as possible to avoid excess odour. We're continually making improvements to our loading practices to reduce loading times, and ensure loaded trucks are appropriately covered as quickly as possible.
Can asphalt production affect the health of those living and working around your sites?
As with most industrial plants which use chemicals, asphalt plants can emit very low levels of various elements. However, there is no current scientific evidence that these levels of emissions pose any significant health risk to the community.
Factors such as the distance of neighbours from the plant site, the dilution of elements as they travel through the atmosphere, and the temperatures used during production, have an influence on the level of risk. Boral has produced a brochure - Asphalt in your Community - which offers more information about our asphalt sites and their associated community health aspects.
What happens if there’s a fire or spill at an asphalt plant?
All of our Asphalt sites have an emergency management plan (EMP) which is activated in the event of a fire, bitumen or product spill.
The highest risk of fire at an asphalt site is if fumes in confined spaces, such as our storage tanks, find an ignition source. For this reason, extensive and strict controls are in place at the sites around the use of naked flames and smoking.
A spill of asphalt or bitumen does not necessarily mean a fire will result. Unless it is more than 40 degrees Celsius, bitumen cannot travel more than a few metres nor can it penetrate the ground more than a few centimetres before solidifying. If spilt, the material is simply collected for re-use or disposal.
We also work to ensure that local emergency services are familiar with our sites and the potential hazards that we work to avoid so that in the event of an incident, all parties are prepared to respond.
Can asphalt be recycled?
Yes. Old road ‘profilings’ (surfaces) can be collected and turned into Recycled Asphalt Product (RAP), depending on the make-up of the original road and the prevailing environmental standards applying to the particular location.
RAP is increasingly being incorporated into new asphalt production due to the environmental and economic savings it creates. The use of RAP means avoiding the use of new natural resources as part of the process.
Some of our plants have the capacity to include up to 30 percent of RAP in their production, an amount we’re continuing to try and increase as we move forward.
What is ‘spray seal’?
In some areas, roads are resurfaced using the ‘spray seal’ technique, a service which Boral Asphalt provides. The prepared road surface is ‘sprayed’ with a bitumen layer, then ‘sealed’ with a load of the appropriate grade of aggregates.
Boral has spray seal depots located throughout Australia from which this simple road surfacing solution can be offered. Regular spray seal customers include local Councils.
What is Boral Asphalt Contracting?
Another service offered by Boral Asphalt, the Contracting team provides a complete road surface preparation and installation offering. This includes the use of Boral’s road laying equipment, mobile asphalt production, and traffic control. You can view Boral Asphalt's Company Profile Brochure or view our products online.
Boral Asphalt has operations and services located in most states and territories of Australia. Click here to view where we are.