Concrete pavement samples in engineer Liv Haselbach's laboratory at Washington State University.
Click on image for full size
Courtesy of Alan Abdulkader, Washington State University
How Solid is Concrete's Carbon Footprint?
News story originally written on June 30, 2009
Lots of things are made of concrete - houses, apartment building, and even schools. Sidewalks are often concrete too. Making concrete releases greenhouse gas into the air, which causes Earth to warm. But scientists have found that over many years concrete can pull some greenhouse gas out of the air too, so it might not cause as much warming as we thought.
Concrete is made of sand and rocks mixed with cement, which holds it all together. When cement is made from limestone, it releases carbon dioxide, a greenhouse gas, into the air. Also, it takes energy to make limestone into cement. The energy usually comes from fossil fuels which release carbon dioxide to the atmosphere when they are burned.
However, scientists have found that over many years concrete can take carbon dioxide out of the air. So the buildings, sidewalks, and other things that are made from concrete are able to capture some greenhouse gas too. Liv Haselbach, an engineer at Washington State University studies how concrete blocks like the ones in this picture take in carbon dioxide.
Understanding how carbon dioxide is absorbed into concrete may help us find ways to make this happen faster. Taking more greenhouse gas out of the atmosphere would help slow global warming.
Last modified June 30, 2009 by Lisa Gardiner.
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