The world produces about 30 billion tons of concrete a year, a massive amount. The building material is a mix of sand and gravel held together by a paste of cement and water.
Concrete can also absorb CO2 from the ambient over its lifetime, though this is a fairly slow process.
A new concrete recipe developed by Purdue University researchers can double this carbon-absorbing speed. The key ingredients in the new formulation are tiny nanoscale particles of titanium dioxide, which is also used in sunscreens and paints.
https://www.anthropocenemagazine.org/2021/02/new-concrete-soaks-up-twice-the-carbon/