Environmentally speaking, concrete countertops present a mixed bag of bad and good.
On the bad side, concrete uses a lot of cement. Cement production requires a great deal of energy for the high-temperature processing of limestone and other materials. Between the different stages of cement manufacture, the cement industry is one of two primary producers of carbon dioxide (CO2), creating up to 10 percent of worldwide emissions of this gas [sources: van Oss and Brehm]. Limestone, sand, clay and aggregates are mined from the earth by tons to make concrete, disrupting habitats and leaving vast craters in the earth. Additionally, making concrete removes fresh water from the environment, currently at the rate of over 2.2 trillion lbs (1 gigatonne) per year [source: van Oss].
Heavy metals, which can cause health problems and contaminate soil, water and food supplies, are part of the make up of some pigments, such as chromium oxide and cobalt blue. Acid stains and sealants can release Volatile Organic Compounds (VOC) that pollute the air, creating respiratory problems and contributing to the formation of ozone in the Earth's atmosphere.
On the good side, your concrete countertop probably won't need to be replaced for generations. With care and maintenance, it can last for 75 years. When it needs replacing, the countertop can be recycled for different uses or broken into aggregate for fresh concrete.
Because concrete is so important to our everyday life, numerous institutions work to reduce its negative impact. The Concrete Countertops Institute promotes the use of waste materials as aggregate and cement supplements. Civil and environmental engineers at the Massachusetts Institute of Technology are experimenting with reorganizing the nanoparticles in concrete to reduce CO2 emissions. And the U.S. Army has developed technology that makes concrete repel water without harmful sealants.
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