Concrete is all around us, being the second most widely-used substance in the world. It’s a simple material to make, yet buildings made of it can last for thousands of years. It is also responsible for about 8% of all CO2 emissions, so it is the target of research to try to make it “greener”.
Concrete’s CO2 emissions come from its critical ingredient, cement. At our recent perspective we heard from Jose Garcia PhD, assistant professor at Sac State researching concrete and explaining how to shrink its CO2 footprint. Check out the video.
Prof Garcia broke down why concrete has high emissions. Most importantly, what Garcia most frequently corrects people on, concrete and cement is not the same thing. If Concrete were cake, cement would be the flour. Cement is to concrete as flour is to cake, both binding agents holding things together. Cement holds aggregates (like sand, iron ore and rock) together to form concrete. To make cement limestone is heated to 1000 C resulting in the calcium carbonate becoming calcium oxide (Quick lime) and CO2. They then combine the quick lime with aggregates to create cement.
For every 1 kilogram of cement that is produced, there is 1 kilogram of carbon dioxide that is produced. 60% comes from the chemical reaction, and 40% comes from the burning of fossil fuel. While cement is carbon intensive, concrete has the opportunity to be more environmentally friendly. Waste materials that would normally end up in landfills like fly ash, slag cement, and silica fume, can be added to concrete, reducing its emissions impact.
Professor Garcia researches alternatives to cement called Supplementary Cementitious Material and Portland limestone cements. He looks at how they could be used in more specialty applications. There are even opportunities for concrete to be injected with CO2 collected from the atmosphere making it stronger. But there are also issues with that.
Make sure you watch the video and look for us to invite Professor Garica back.
ABOUT THE AUTHOR
Giovanni Smith is currently a junior going to Sacramento State University. Working towards his BA in mathematics with an emphasis in statistics and a minor in computer science. He wants a career using his knowledge in mathematics and coding.
"I’m excited to be working with CleanStart to learn more about the energy space and apply my mathematics to help solve real-world problems." - Giovanni Smith