Mixing the unmixable to produce a greener tyre

Dutch material scientists have been hard at work, exploring the chemical reactions that create a fuel-saving tyre and developing a method of predicting when concrete will crack in a wet and salty environment. But will nature’s forces always win the erosion battle, or can buildings and tyres withstand the pressure? Does cracking inevitably lead to crumbling, and how long will your tyre roll for?

How to predict cracks in bridges (courtesy NWO)

How to predict cracks in bridges (courtesy NWO)

Silica and rubber were finally united by Michelin in the mid 1990s. The result was a tyre with a 30% lower rolling resistance that reduced a car’s fuel consumption by 5%. Now other manufacturers - who have stuck with the tradition of using carbon black to strengthen rubber in tyres – are finally waking up to the lure of silica. But the switch won’t be easy.

“Technologically, the problems involved in using silica are enormous,” Professor J.M.W. Noordermeer from the University of Twente told edie. His student, Louis Reuvekamp, has been investigating how Michelin fused silica and rubber using organosilane as a coupling agent.

While a minimum of 130°C is needed to trigger the coupling agent’s reaction with silica, temperatures above 150°C vulcanise the rubber, making it too hard for processing. Working within the tight 20° window, Reuvekamp experimented with the silica’s grain size to find the optimum particle size to reduce the tyre’s rolling resistance.

A tyre should roll smoothly, but must also protect against skidding, as well as lasting long enough to pay for itself. It’s the magic triangle that manufacturers work to, balancing a low rolling resistance with a high wear and skid resistance, says Noordermeer. Michelin’s secret formula overcame the difficulties of mixing the unmixable. Now other companies are eager to follow.

Over at Delft’s University of Technology, another Dutch scientist has developed a computer model that calculates the rate at which salt and moisture penetrate reinforced concrete. Sander Meijers’s model can be used by developers to assess the lifespan of bridges sitting in water and help architects fine-tune the design of new bridges and dams. Planners can also work out how much salt gritting concrete structures can withstand.

Maya Sule from the same university has been taking concrete to its limit, testing its stress levels during the hardening process that forms the concrete. Reinforced high-strength concrete has a tendency to crack if the concrete is poured into a restricted space, because concrete expands and contracts as it forms.

Sule has discovered a method of making cheaper concrete by reducing its water content, which in turn reduces the cooling time and requires fewer contraction joints to absorb the expansion, saving on materials and costs.



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