Researchers have found a way to convert rubber from discarded tires into the strong carbon nanomaterial graphene. Adding this graphene to concrete makes the concrete stronger and more sustainable. Concrete has become the most-produced material in the world. Its production results in nine percent of global carbon emissions. To reduce those emissions, researchers have tried to boost its ability to absorb carbon dioxide or use less carbon-intensive alternatives to cement, the main ingredient in concrete.
The new research presented in the journal Carbon could shrink the carbon footprint of concrete while addressing the problem of waste tires. Almost a billion tires are scrapped around the world every year. Around 16 percent of them end up in landfills, but most are either ground up for other uses or burned for fuel, including fuel for cement kilns. Last year, a team in Australia made a road-building material by blending crushed concrete with shredded tires.
The team from Rice University and C-Crete Technologies in Stafford, TX decided to convert waste tires into graphene, which has been shown before to strengthen concrete. They used a graphene-production technique developed at Rice called flash heating, which involves superheating carbon sources such as food waste or plastic with a jolt of electricity. The process removes everything else besides carbon atoms, which rearrange into graphene flakes.