Road makers turn to recycled plastic for tougher surfaces

OF ALL the plastic produced since the 1950s, less than 10% has been recycled. The vast majority ends up being dumped, most of it in landfill. Some is left to litter the natural environment, where it can get into rivers and wash out into the sea (see ). The plastic-waste problem will worsen before it gets better: some 380m tonnes of the stuff are likely to be made this year. That is more than three times as much as the 120m tonnes of bitumen produced annually, most of which goes into building the world’s roads.There is a connection. Just as plastic is derived from petrochemicals, bitumen is produced as a by-product of refining oil. Both are polymers, which consist of long strands of molecules bound together firmly. It is this characteristic that makes plastic strong and contributes to its great longevity. Such features are also useful for road builders, who use hot bitumen to bind together aggregates made from broken rocks and stones, into what is commonly known as asphalt. All of which has got some people thinking: why not swap one polymer with another?