"With the increase of road transportation and the consequent demands for higher quality roads, the enhancement of asphalt properties are becoming more critical. The best way to improve the engineering properties of asphalt is its modification with small amounts of selected macromolecular materials".
- Resurfacing a road with a polymer modified bitumen emulsion
Photo courtesy of Colas
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In 1902, the first road using asphalt modified with natural rubber was built in Cannes, France. After WWII, synthetic macromolecular materials were developed and tested. Old tires have already been used successfully as a cheap source of rubber for asphalt modification. Unfortunately only around 40 percent of old tires are being recycled at this time. Research into using other post consumer materials such as plastics and industrial waste materials as asphalt modifiers is underway.
"Before such materials are used, however, thorough research has to be done to investigate the following aspects:
- impact of waste materials on the performance and durability of final asphalt pavements
- potential environmental hazards associated with technologies incorporating these materials into the asphalt mixes
- potential environmental hazards associated with recycling of old pavements containing these materials
- cost of new technologies and their impact on the economy of asphalt pavements"
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Recycling - re-using existing road material
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Cold in-situ road recycling involves the pulverisation and re-profiling of the failed road surface. Binders such as foamed bitumen or cement are then applied to the new surface and compacted to form the new base. This is then overlaid with a new wearing course. (a thin surfacing with negative texture Which has anti-skid properties and will resist the stresses imposed by braking and turning vehicles.)
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"Examples of the negative impact are release of fumes associated with hot technologies in both paving and roofing applications, the release of hydrocarbons into the atmosphere in cold applications and the potential leaching of petroleum fractions into surface and ground waters."
