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Volcanic Rock Could Slash Cement Manufacturing Emissions By Two Thirds

Volcanic Rock Could Slash Cement Manufacturing Emissions By Two Thirds

August 27, 2021

Scientists at Stanford University have claimed that replacing one of concrete’s main ingredients with volcanic rock, could slash carbon emissions from the manufacturing process of the material by almost two-thirds.

Concrete is one of the most used building materials on the planet and one of the world’s largest industrial contributors to global warming, releasing as much as 8% of annual carbon dioxide emissions during the manufacturing process, with demand expected to rise substantially in the coming decades. However scientists as the University of Stanford have proposed a fascinating solution - to eliminate the chemical reaction which releases the CO2, using volcanic rock.

“If we’re going to draw down carbon emissions to the levels necessary to avert catastrophic climate change, we need to change the way we make cement,” Vanorio said, associate professor of geophysics at Stanford University.

Vanorio proposes eliminating limestone altogether and starting instead with a rock that could be quarried in many volcanic regions around the world. “We can take this rock, grind it and then heat it to produce clinker using the same equipment and infrastructure currently used to make clinker from limestone,” said Vanorio.

Image of lava lake.

 How does it work?

- Limestone is the main ingredient in modern concrete, which is crushed and baked at a high temperature. Generating this amount of high heat involves burning coal and other fossil fuels, therefore increasing carbon emissions.

- This high level of heat triggers a chemical reaction. This chemical reaction releases carbon that would otherwise remain locked in limestone for hundreds of millions of years.  

- The new cement prototype will eliminate the CO2-releasing chemical reaction by making clinker (marble-sized gray lumps, which are then ground into the fine powder we recognize as cement) with  volcanic rock that contains all the necessary building blocks for the material, but none of the carbon.

- Using the volcanic rock will essentially eliminate the carbon from the process during this stage of manufacturing.

- There is additional evidence that the new material would be more durable than the current concrete that is used, another added benefit. When under a microscope the scientists observed long chains of molecules which look like tangled fibers. Similar structures to these molecule chains exist in rocks which were used for Roman harbors, which survived over 2,000 years of assault from corrosive saltwater and waves, conditions where modern concrete would typically crumble within decades.

Article Credit -
Stanford University