Bouncy pavements

C&I Issue 3, 2020

Softer road surfaces incorporating waste tyre rubber could improve road safety and solve a big disposal problem at the same time, according to researchers.

The problem with earlier asphalt samples made with tyre rubber was its relatively low durability, explained Viveca Wallqvist of RISE Research Institutes of Sweden. This is because the porous rubber particles were found to absorb the bituminous binder holding together the aggregates and preventing the road from cracking.

To get around that problem, the researchers now pre-treat the rubber in a low temperature process before adding it to the mix, Wallqvist said.

The new shock absorbing pavement is funded as part of the EU’s SaferUp! project and will be tested in parts of Sweden this year.

‘[Over a million] years ago our feet developed for grassland environments, then 7000 years ago came the first streets, designed for wheels, and suddenly all our environments have hard surfaces. But why so hard?’ asks Wallqvist. ‘We could be the last generation to walk on hard surfaces, because why should we?’

Every year 36,000 older adults die from falls and 56% of these occur outdoors. Injuries from falls cost an estimated €109bn annually – more than the total funding for the EU’s Horizon R&D spending, she pointed out. Meanwhile, around 2000 cyclists are killed every year, with 17% of fatal injuries to cyclists caused by accidents not involving other vehicles.

In silico modelling studies have now been carried out to investigate to what extent rubber surfaces will reduce the extent of injury.

Every year 3bn tyres are discarded globally. In the EU, landfill is no longer allowed. However, in the US 16% are landfilled, 43% are combusted and 25% are used as ground rubber.

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