Greening Portland Cement

Last week, I talked about EPS and that its positive or negative environmental impact really depends on how it is used. Portland cement, the primary ingredient of concrete, is different. Complaints about Portland cement stem from the embedded energy needed to make Portland cement and the greenhouse gases given off in its production. But Portland cement is used in almost all long term construction in the world today, so the issue becomes, how do we use as little Portland cement as possible to create a long lasting, permanent structure? There are several things you can do to minimize the amount of Portland cement required to make a house.

• First, you can use a building technique that uses the minimum amount of concrete structurally required. In our BuildFast panels, for example, only 1 inch on each side (2” total) is required to build, unlike a reinforced concrete wall that would require 6-8” of concrete. Our solution requires about 12 cubic yards of concrete to make a 500 sq ft house, versus a reinforced concrete wall that would require 48 cubic yards.
• Second, you can incorporate fly ash in the concrete mix to reduce the total amount of Portland cement required. Fly ash, a waste product of the coal industry, can substitute up to 20% of the Portland cement without compromising structural strength. I have even heard that up to 50% can be substituted, but more research is needed.
• Finally, there are some interesting alternatives to Portland cement becoming available. Several companies are introducing alternatives to Portland cement including Grancrete, Gigacrete, and others. I know Gigacrete has been gaining a lot of traction recently, and they have received funding to build a full production facility for their Stuccomax product. I met with the inventor, Andrew Dennis, a few months ago, and I believe they have a very exciting product which I look forward to the opportunity of trying it out. Unfortunately for us and the billion people who need housing today, I believe they are a long way from reaching the economies of scale that would be needed to offer their products at a price most people could afford, and with broad international distribution.

Any other ideas out there on ways to reduce the amount of Portland cement used in construction? I’d love to hear your input.