Asphalt Types
At Roads 2000, we’re at the forefront of asphalt innovation, giving you the biggest and best range of options when embarking on a new project.
We’re industry leaders in developing environmentally friendly, sustainable mixes for projects. Our Wangara plant along with our mobile asphalt plants ensure we can deliver high-quality recycled asphalt to wherever it’s needed around Perth.
Asphalt Types
Stone Mastic Asphalt
Stone mastic asphalt, also known as stone-matrix asphalt, is an increasingly popular asphalt mix due to its ability to disguise reflective cracks in the open textured surface and is used for all types of roads.
Stone mastic asphalt is a gap graded wearing coarse mix with a high proportion of coarse aggregate which interlocks to form a skeletal structure to resist permanent deformation and bound with a mastic mortar. It is delivered, laid and compacted while hot.
At Roads 2000, we manufacture our own stone mastic asphalts and can produce and lay mixes with maximum stone sizes of 10mm and 7mm. We use Class 320 bitumen exclusively for all stone-matrix asphalts.
The IPWEA/AAPA Technical Specification for Supply and Laying of Hot Asphalt Road Surfacing (Rev 3) provides advice on the design for SMA. Roads 2000 uses Class 320 bitumen exclusively for all stone mastic asphalts.
Other things to consider:
When laying stone mastic asphalts, it is recommended that layer thicknesses are not less than 3 times the stone size or greater than 5 times the stone size. The increased thickness is to limit the possibility of “dragging” the mat. When laying multi-layer asphalts, the previous layer must be allowed to cool below 40°C. Compaction should be provided by only static steel rollers and vibratory or rubber-tyred rollers should not be utilised. SMA is at high risk of flushing immediately following installation and/or in high temperatures. Main Roads Specification 502 for SMA recommends that no traffic be allowed on the completed asphalt if it has a temperature in excess of 40°C. This can be offset by gritting and/or the application of water to (i) reduce contact with the surface binder and (ii) cool the asphalt to the required temperature. Roads 2000 does not recommend that SMA is used in car parks or roundabouts (ref R2K-05). In the USA, polymer is utilised in the binder for intersections surfaced with SMA.
Dense Grade Asphalt
Dense grade asphalt is implemented in areas with a high volume of traffic to cope with the increased load – highways, arterial, industrial and distributor roads.
Dense grade asphalt is a continuously graded mixture of coarse and fine aggregates, mineral filler and bitumen, produced hot in a mining plant and delivered, laid and compacted while hot.
We manufacture our own dense grade asphalt and can produce and lay mixes with maximum stone sizes of 20mm to 7mm. We use Class 320 bitumen exclusively for all dense grade asphalts, which minimises issues related to ‘soft’ asphalts like flushing, scuffing and shoving.
The IPWEA/AAPA Technical Specification for Supply and Laying of Hot Asphalt Road Surfacing (Rev 3) provides advice on which dense grade designs should be used in particular circumstances.
Other things to consider:
If a dense-graded asphalt surface needs to be immediately opened to traffic, consider spreading sand lightly on the surface to minimise scuffing while the asphalt is still hot. Please ensure slippery surfaces are signposted with the appropriate warning signage. In areas where there are significant braking and turning movements and/or increased commercial traffic, it is recommended that ‘intersection’ mixes are used or alternatively stiffer and/or modified bitumen binders within the mix design. When laying dense grade asphalts, it is recommended that layer thicknesses are not less than 2.5 times the stone size or greater than 5 times the stone size, e.g. 10AC should be no thinner than 25mm or thicker than 50mm. When laying multi-layer asphalts, the previous layer must be allowed to cool below 40 degrees celsius. Compaction should be initially provided by a steel roller and back-rolled with a rubber-tyred roller.
Open Grade Asphalt
Open grade asphalt is used all over Australia and overseas to provide a safe driving surface in wet weather conditions. It is also used to reduce noise levels in urban areas.
Open grade asphalt is a porous asphalt mix. The grooves and large voids provide a safe surface for motorists in wet conditions, as the voids allow for easy draining and eliminate any standing water that may be left on the surface of the road.
At Roads 2000, we manufacture and lay our own mix of open grade asphalts for road projects all around Perth and Western Australia.
Contact Us
Roads 2000 can provide advice to clients on the mix designs where required.
For more on our asphalt mixes, contact us on (08) 9202 0800 today and we’ll be happy to discuss your asphalt requirements with you.