You probably didn’t wake up this morning pondering concrete. But look around and chances are, you’ll see the substance in abundance. Buildings, walls, bridges, parking garages … you could write a (not very interesting) book on all the places you see concrete.
The mixture of cement, aggregate, and water has a longevity that’s the stuff of legend; just look at the Roman Pantheon. But roads get replaced, old buildings get demolished, and, every year, we’re left with mountains of concrete rubble. In 2010, Germany alone produced an estimated 130 million tons (117.9 million tonnes) of construction waste.
Further complicating matters is the impact on the environment. With cement production as the primary culprit, concrete manufacturing contributes an estimated 8 to 15 percent of global CO2 production. Concrete recycling is limited, with the present shredding method producing enormous amounts of dust, and only utilizing downgraded leftovers.
Source: gizmag.com