The Conco Companies recently completed the massive,
continuous mat pour for the Salesforce Tower that is currently under
construction in downtown San Francisco.
The job required approximately 12,000 cubic yards of concrete, and was
enough concrete to fill almost four Olympic size swimming pools. We are pleased to report that the foundation
was poured using “green concrete”, which is concrete produced from recycled
materials and generates lower CO2 emissions as compared to conventional
concrete.
While concrete is recognized as an
excellent creative and effective sustainable building material, a conventional
cubic yard of concrete contains by weight approximately 10 percent of
cement. CO2 emissions occur during the
production of the cement, and for each ton of cement produced; it creates about
0.9 tons of CO2 emissions.
To produce the cement used in
concrete, it requires heating pulverized limestone, clay, and sand to 1,450 °C
with coal or natural gas. As a result in
2009, it was reported that five percent of all carbon dioxide emissions
throughout the world were a result of producing 2.8 billion metric tons of
cement.
“Green concrete” is defined as
concrete that uses other material as a partial or complete replacement for cement
or fine or coarse aggregates, and the substituted material can be
waste or residual products obtained from manufacturing industries. The goal of creating a greener concrete is to help
reduce greenhouse gas emission, to reduce the use of natural resources such as
limestone, shale, clay, natural river sand, natural rocks, and to recycle waste
materials that would otherwise end up in landfills. Today there are many people researching a variety
of methods in order to create cements that do not produce as high of an amount
of CO2 emissions.
The
Conco Companies are the foremost supplier of concrete services for
the Western U.S. We have built a reputation on superior concrete formwork,
reinforcing, place and finish, shotcrete and other ancillary services that
benefit from our vast experience. Our
four regional offices serve California, Colorado, Oregon, Washington, and Nevada.
Source:2.technologyreview.com/article/418542/tr10-green-concrete/
