Making cement is an extremely carbon-intensive process. It’s produced in factories with massive kilns where raw materials, like limestone, clay, and shale, are heated to temperatures up to 1550 degrees Celsius, then ground into a powder. Heating the cement minerals to such high temperatures poses a sustainability concern, says Kemal Celik, professor of civil engineering at New York University in Abu Dhabi and the director of the Advanced Materials and Building Efficiency Research (AMBER) Laboratory. Producing cement accounts for around 7% of global CO2 emissions.
Celik and his team 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 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. The team has already conducted tests showing that it’s just as strong and adaptable as ordinary concrete.
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