Cement from desalination: double benefit

Cement and concrete have a serious carbon problem. Making cement uses lots of energy and the chemistry of it releases greenhouse gases. "Producing cement accounts for around 7% of global CO2 emissions."

At the same time, desert nations along the sea making potable drinking water from seawater have to do something with the brine that is left over. Usually they pump it back into the sea which can affect sea life, especially if they don't pump it far out to sea.

Some smart folks in Abu Dhabi think they've come up with a solution to both.

This fact [CO2 emissions], Celik says, got him interested in finding a better way to make the material. He and his team already knew that magnesium oxide, a mineral found in salt deposits like lakes and salt flats, could be converted into a type of cement. In the United Arab Emirates, where Celik and his team work, they realized they could tap the over 70 operating desalination plants for access to brine left over from the process of purifying seawater, which would otherwise just be dumped back into the Gulf. Synthesizing the magnesium oxide in brine into a cement-like substance requires much less heat than making ordinary cement. And, Celik says, as magnesium oxide cement hardens over its lifetime, it absorbs carbon dioxide over time to gain strength, potentially making it a carbon-negative building material.

https://www.fastcompany.com/90338907/a-new-breakthrough-lowers-the-footprint-of-making-both-concrete-and-fresh-water