Scientists from the Texas-based Rice University have optimised a process to convert waste rubber tyres into graphene that can be used to strengthen concrete.
Using a green technology called the “flash” process introduced by the Rice University lab of chemist James Tour, which can convert bulk quantities of any carbon source into valuable graphene flakes, quickly and at a fraction of a cost. These carbon sources are exposed to a jolt of electricity that removes everything but carbon atoms from the sample. Those atoms reassemble into valuable turbostratic graphene, which has misaligned layers that are more soluble than graphene produced via exfoliation from graphite. That makes it easier to use in composite materials.
Rubber proved more challenging than food or plastic to turn into graphene, the scientists said, but the lab optimised the process by using commercial pyrolysed waste rubber from tyres. After useful oils are extracted from waste tyres, this carbon residue has until now had near-zero value.
Tour said that tyre-derived carbon black or a blend of shredded rubber tires and commercial carbon black can be flashed into graphene. Because turbostratic graphene is soluble, it can easily be added to cement to make more environmentally friendly concrete.
The research led by Tour and Rouzbeh Shahsavari of C-Crete Technologies is detailed in the journal Carbon. The Air Force Office of Scientific Research and the Department of Energy’s National Energy Technology Laboratory supported the research.