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A New Guide Walks Homeowners Through the Process of Building 'Green' By Katherine Salant, washingtonpost
According to the product category summaries, even the most seemingly innocuous product can have its downside.
For example, cement is the critical ingredient that makes sand and gravel bind and become hardened concrete. Its manufacture is both energy intensive and polluting. When a ton of cement is made, up to a ton of carbon dioxide is released into the atmosphere. The environmental effects of cement can be lessened, however, if the amount of cement mixed into concrete can be reduced without affecting its structural integrity.
One cement substitute is fly ash, itself an industrial waste created at coal-burning power plants. Moreover, fly ash actually strengthens the concrete because it changes its chemical properties. Concrete will be greener still if you substitute recycled glass fragments for gravel. The fragments are made in part from recycled glass bottles.