Is Concrete a Green Building Product?

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It’s true that the production of concrete creates greenhouse gases (what doesn’t?); its components of stone and sand must be mined from the earth, and our precious resource of water must be consumed to make it, but there are some green aspects too…let’s hope so since it is used more than any other man-made material in the world!components of concrete

Concrete is made up largely of local materials (reducing transportation pollution; by-products of the coal and steel industries–fly ash and blast slag–are being incorporated into concrete; and structures made from concrete are energy-efficient and long-lasting. See my previous post about Insulated Concrete Forms here.

So, what does concrete consist of? The majority of it is composed of cement (dry powder binder typically consisting of limestone, clay minerals, and gypsum), a course aggregate (gravel limestone or granite), a fine aggregate (sand, fly ash, or slag), water, and chemical admixtures (accelerators, retarders, air-entrainers, plasticizers, pigments and corrosion inhibitors).

Much testing and research is conducted to increase the amounts of Supplementary Cementious Materials (fly ash, blast slag, silica fume, fine glass powder, and ground limestone). Water recycling programs are frequently in place. Concrete debris now routinely avoids the landfill through recycling efforts. It is broken down, steel rebar and other metals are removed and recycled elsewhere, and the crushed concrete is reused as road base, fill, landscaping material, soil stabilization, and sometimes as aggregate for ready-mixed concrete and asphalt.

According to Wikipedia, “Geopolymer concrete is a greener alternative to ordinary Portland cement made from inorganic aluminosilicate (Al-Si) polymer compounds that can utilise 100% recycled industrial waste (e.g. fly ash and slag) as the manufacturing inputs resulting in up to 80% lower carbon dioxide emissions. Greater chemical and thermal resistance, and better mechanical properties, are said to be achieved by the manufacturer at both atmospheric and extreme conditions.”

A sustainable outdoor use for concrete is pervious pavement, where rain water is able to pass through the concrete to replenish aquifiers and manage stormwater runoff. Pervious concrete can even be used in conjunction with water-storing cisterns.

The lighter color of concrete, as opposed to asphalt, also reduces the heat island effect in cities by reflecting the sun back into the atmosphere, along paved surfaces, instead of retaining it in the city.

An interior application of concrete floors is useful for absorbing heat from the sun to warm a home’s interior. Check out my previous post about thermal mass here.


(graphic from Portland Cement Association)

Tag(s): Green Building


2 Responses to “Is Concrete a Green Building Product?”

  1. greg on September 11th, 2008 6:10 pm

    We used 30% fly ash concrete for our foundation work of our home (see The concrete is as strong as ‘regular’ concrete, but is using more recycled, local material. Most fly ash is sent to landfills, so saving some of it to put in our home was valuable to us even though it cost about 10-15% more.

  2. Ben on October 21st, 2009 10:31 pm

    Please tell me I did not just read an article that said, “according to wikipedia”! On another note, just because we use so much concrete and ‘hope’ it is green, does not automatically make it so. Green aspects does not make a green product. I was trying to find the green value of concrete and this article seems to reinforce my other findings that concrete is NOT the way to go.

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