Why is concrete environmental unfriendly?

In its final form, as waste, concrete is far from being either biodegradable or environmentally friendly. It generally has to be smashed up and removed in chunks. One of the benefits of working with concrete is that it is adaptable, hard wearing and long lasting, but once it has started cracking, or becoming uneven, then it needs to be replaced, or covered with further layers of new concrete. (via)

@MissAnthrope I don’t quite agree. Concrete may not be “biodegradeable” like paper is. It won’t disappear in a few weeks, but it really wouldn’t take too many decades for it to be broken up into harmless rock dust by nature if left unattended. It’s far, far, far more “biodegradeable” than, say, plastic or tires.

I don’t know why they’d say that @rebbel. What other kind of flooring or base would you want under your house?

I remember hearing a program on NPR about “green” concrete that actually put something back—I think it was oxygen into the air. The program was talking about what a difference it could make if this material were used for sidewalks, large structures like airports, etc. I wish I could remember what it was called. It sounded marvelous.

Because most of the time the so-called portland concrete is being used instead of far better alternatives.

See for example

http://www.zeobond.com/cement-sustainability.html

“Ordinary Portland Cement (OPC) is the grey powder that is mixed with water, rock and sand to create concrete, and is the largest commodity product on the planet with over 2.5 billion tonnes produced annually. It is also the third largest source of man-made CO2 emissions, representing approximately 5% of all emissions.

OPC is the dominant source of CO2 emissions from concrete (70%+) and the primary source of emissions in road, infrastructure and construction projects – around 20 – 40% of total project emissions according to the state of Victoria’s roads authority, VicRoads, and other bodies’ internal investigations. This makes reducing the amount of OPC used to make concrete a top priority. Zeobond can totally replace OPC!

OPC is made primarily of 60% CaO, 40% SiO2 and some Al2O3, Fe2O3 and SO3. The source of calcium is limestone, which is mainly calcium carbonate, CaCO3, and is obtained through quarrying.

In manufacturing a tonne of OPC approximately 0.60 tonne CO2 from the CaCO3 CaO + CO2 calcination reaction. In addition, approximately 0.40 tonne CO2 is produced from fossil fuels used to generate the energy to heat the materials to 1400 degrees C. In total the manufacture of a tonne of OPC therefore emits approximately 1 tonne CO2.”

I read the following book and it is awesome:

http://books.google.com/books?id=nKKxbu8iCnIC&pg=PA163&lpg=PA163&dq=factor+five+concrete+hargroves+energy&source=bl&ots=jRCueJjbmd&sig=tuLhSOMfcO4KNXp1nvDFcBILQ5U&hl=en&ei=OBEKTdrKDIS38QPjnZVO&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBIQ6AEwAA#v=onepage&q&f=false

It’s definitely an energy-intense thing to produce.