You have probably seen, walked or driven over rubberised asphalt and never knew what it was, so what is it? It’s a combination of asphalt concrete and finely ground down, used rubber tyre material that has been used as a road surfacing material in some parts of the world since the 1970’s. It has proven itself to be a superior product to normal asphalt in many ways, including its general wear capabilities, resistance to cracking, and reduction of traffic noise.
It also provides a great alternative way to recycling scrap tyres than dumping them in landfills. The rubberised asphalt production method involves the grinding down of used tyres and then removing any fabric and steel fibres, and finally mixing what is left over with a binder and then an asphalt cement mix. This mixture is then laid the way as regular asphalt surfacing material.
History and Production
In an attempt to focus on road surface degradation in 1971, the City of Phoenix (United States), applied rubberised asphalt (usually employed as a chip seal layer) to a section of road as a temporary solution. Surprisingly, against pessimistic expectations, the quick fix demonstrated to be extremely successful and the road did not require resurfacing for a further 20 years. This led to the specific development of rubberised asphalt as a dedicated road surface solution, and why surfacing in Norwich has become renowned for its wonderful abilities.
After removal of all fabric and steel reinforcing, and being ground into an aggregate with the close consistency of ground coffee, the crumb rubber, as it is known, is collected and transferred to an asphalt production facility. The crumb rubber is then blended with a special binding agent and transported to a hot asphalt facility where it is combined with traditional hot asphalt cement mix made from asphalt and an aggregate of fine stone or sand. This is the final mix that gets applied to the road surface using professional surfacing technology.
Rubber-treated asphalt provides a number of benefits over regular mixes. Roads surfaced with it tend to last and age better than regular surfaces because of its flexibility of the rubber and the antioxidants from the tyre material. Rubberised asphalt surfaces also resist the formation of ridges, and skid resistance is superior, making it ideal for safer driving conditions.
Rubber-treated asphalt surfaces are also well known to produce a lot less road noise, in some cases returning up to a 12 decibel decline with averages between four and five decibels. And maybe one of the most important advantages of the use of rubberised asphalt is the superb environmental impact it has had, with somewhere between 500 and 2,000 scrap tyres going into each lane mile of road surface. This simply and positively means that less tyres end up creating pollution and other environmental issues in landfills, which further enhances the value of the process.
Rubberised asphalt is definitely here to stay!