Concrete is an incredibly useful and versatile material. It is made from sand, gravel, water and cement, and can be cast into different shapes, becoming very hard as it sets. It is one of the most commonly used substances in the construction industry.
Unfortunately, cement production is a significant contributor to greenhouse gas (GHG) emissions. Each year about 4 billion tonnes of cement is produced, which accounts for 8 % of global CO2 emissions (about 2.7 billion tonnes of CO2 per year).
Researchers at the Johannes Gutenberg University Mainz (JGU) in Germany have now developed a method that radically reduces CO2 emissions from cement production. The process replaces the calcination of lime with mechanical grinding of the raw lime and sodium silicate. Calcination requires temperatures of 1000 to 1500 degrees Celsius, while grinding requires no heat and requires only about 10 % of the energy. Most of the CO2 emissions come from the calcination process because one molecule of CO2 is produced for every molecule of calcium oxide produced, which will be entirely avoided through the grinding process.
The process has only been tested in the laboratory, and a lot of research is needed to determine whether and how the process can be scaled up to be economically feasible.