Lightning Strikes Concrete Recycling

Researchers in Germany are developing a method to break concrete down to its basic components – aggregate and cement – for more efficient recycling of waste concrete. The technique, which sends extremely quick lightning bolts through concrete submerged in water, could reduce emissions related to concrete production and incentivize re-using the hundreds of tons of waste concrete produced worldwide every year.

German researchers at the Concrete Technology Group are using lightning bolts to revolutionize the recycling possibilities of concrete waste, which totals hundreds of tons of global waste material every year. Current recycling methods shred waste concrete, to limited effect for future use. Based on a method discovered by Russian scientists in the 1940s, researchers at the CTG are sending extremely short electrical impulses – less than 500 nanoseconds – through waste concrete submerged in water. The technique, called electrodynamic fragmentation, directs the impulse down the path of least resistance and through the solid instead of the liquid, which in cement is the boundary between the gravel aggregate and cement stone. The concrete breaks apart with explosive force and returns to its basic components, separating the aggregate from the cement. Project leader Volker Thome said that recovering aggregate from waste concrete would increase the value of recycling exponentially, and an efficient "fragmentation plant" that can process at least 20 tons of material per hour could be ready for market launch in as little as two years.