If you're planning to build a new house, or looking into concrete countertops, you should know about fly ash. It's a waste product from coal-fired power plants, and it can help make your concrete much more green.
Concrete typically contains Portland cement, lime, and aggregate. Adding fly ash to the mix makes concrete that is stronger and lighter, and it reduces the amount of energy-intensive and expensive Portland cement required.
A side benefit is that the particles of fly ash act like microscopic ball bearings, helping the concrete to flow around the forms, which results in a cleaner, more even finish. This is one reason why Syndecrete has such a uniform surface compared to regular concrete countertops. Those little ball bearings also reduce the amount of water needed in the mix, which is why the finished product ends up lighter.
So, when you're getting ready to pour the foundation for that new green house, it's worth a few calls to see if you can get concrete made with fly ash instead.
image via Headwaters Resources fly ash brochure [PDF]