This article looks at three cements that don't emit as much greenhouse gases as does Portland cement. Two are from LaFarge, the other is from Solidia. LaFarge's Aether, which is in the final stages of development, uses "a new generation of clinker developed for lower carbon cements," and could become useful to precasters because it quickly gains in strength. Solidia's product could be the real game changer though since it appears to reduce carbon-dioxide emissions by as much as 70%.