Saturday, May 3, 2008
How concrete can reduce carbon emissions and energy consuption!
For my podcast I looked at how high volume fly ash can reduce carbon emissions and energy use. Cement production uses a fair share of energy and emits a lot of carbon dioxide emissions. For the whole U.S. cement manufacturing accounts for a small fraction of 1% of energy use, and about 1.5% of carbon dioxide emissions. So, I compared two mix designs of concrete, one using just cement, water, and aggregate. The second mix used fly ash, cement, water, and aggregate. If you use as much fly ash as possible to maintain the same strength needed, you can reduce carbon emissions and energy use by 53% in cement manufacturing. Then I compared the concrete needs in a typical highway. 1100 tons of carbon dioxide are emitted per mile of highway made with the traditional mix design I considered. This could be reduced to 510 tons of CO2 per mile with high volume fly ash concrete. The best thing about using high volume fly ash is that its a waste product that already exists! Currently less than 40% of fly ash waste is reused according to the EPA, and in the Coal Combustion Products Partnership has a goal to have 50% of coal combustion by products reused by 2011. With current needs for concrete all over the country I believe we can do better!