Countertops are just one of many uses for concrete in a green home.  In recent years it has come into its own when used as flooring, fireplace surrounds, furniture, and even whole house construction.  

We have to say up front that concrete's eco-friendliness is a topic of debate as the process of making Portland cement, a major component, is not green.  Environmental alternatives to Portland cement are increasingly available and some modern design factors compensate for its use. More about that later. 

The idea of a concrete countertop maybe a real turnoff to anyone who has never seen one, but they are a spectacular addition to a kitchen.  First of all, these are cast by individual companies or individuals, each with his/her secret processes and biases.  Some refuse to turn out a product that doesn't look like what it is - concrete - albeit very pretty concrete.  Others are willing to explore the range, casting their product to resemble marble, limestone, or granite or embossing it to imitate brick, stone, or wood.  During the casting process it can be imbedded with pebbles, recycled glass, seashells, Mother of Pearl, quartz chips, virtually anything a designer can think of.

As an example of the variety available, The Concrete Network which advertises itself as an independent source of information about concrete describes three finishes offered by a single contractor, Buddy Rhodes Studio. 

"1.  Veined: Buddy Rhodes' signature surface. After the surface is worked with pigment-infused concrete, a diamond-impregnated grinding disk zigzags across the slab, revealing marble-like veining in the background. While gently textured, the surface is smooth enough to roll a piecrust or write a letter.

 2.   Steel Trowel: The smooth, mostly monochromatic surface is notable for its obvious trowel marks and subtle variations of light and dark (think of an Italian plastered wall).

 3.   Terrazzo: Glass or marble chips worked into the background create a two-toned mottled effect, adding textural interest under the smooth surface."

Tops can be cast in virtually any shape either on site or in the contractor's studio although the latter predominates.  Concrete sinks of any size or shape can be cast as part of the countertop and other design features such as drain boards or stainless steel racks for hot pans can be incorporated.  A common design is to mix concrete with other countertop surfaces such as soapstone or butcher block.

Color is a real variable in concrete design.  Each contractor uses different processes for mixing his concrete and coloring it so each will have their own list of standard and custom colors.  Even the type of concrete used will vary across the country and affect colors so consumers are always advices to obtain samples before making a color decision. 

Concrete counter tops are very strong - they don't crack or delaminate like old sidewalks - but they do absorb liquids and stains.  Most concrete contractors seal their products using a variety of materials such as polyurethane sealers, oils, or waxes but some use "conditioners" that actually encourage mottling and staining.  If sealers are scratched the surface will become permeable so it is important to use a cutting board with knives.  The type of sealer used will also affect the heat resistance of the concrete and but it is best to use a trivet rather than placing hot utensils on the counter.

At the standard width of 1.5 inches, concrete weighs 18.75 lbs per square foot - slightly more than granite.  The weight, however, is not a problem as it is evenly distributed over the base cabinets or whatever else is built to support it.

Price is the major drawback to concrete counter tops.  1.5 inch countertops range in price from $65 to $125 per square foot with curved tops, cast-in drain boards and sinks raising the price even higher.  For reference, the Eco-Top surface discussed earlier in the week started at $35 psf.