sample+concrete

__ Air pollution and Global Warming: __
- Production of one ton of Portland cement releases approximately one ton of carbon dioxide into the atmosphere, cement is approximately 7 to 15% of concrete by weight - This carbon dioxide along with nitrous oxide and sulfur oxide caused by the energy requirements needed to produce cement all contribute to concrete’s immense affect on global warming and air pollution - 4.7 million Btu of energy is required to make 1 ton of cement, this amount of energy is equivalent to 345 lbs of coal - During the heating process of cement calcination of limestone occurs which consists primarily of the burning off of calcium carbonate from the limestone; this is what causes the release of excess carbon dioxide into the environment during production - 50% of the Carbon dioxide emissions created in concrete production are chemical related, 40% are attributed to fuel and 10% are attributed to transportation and electricity needs

__** Other Environmental Concerns: **__
- Concrete production processes causes environmental impacts at all stages; from damage to countryside due to quarrying for limestone to noise and chemical pollution throughout the process to construction and demolition waste - Construction and demolition debris contribute a considerable fraction to the solid waste created in developed countries (often up to 20%) and concrete is the largest component of this waste - 200 to 300 million tons of construction and demolition waste are generated each year in the United States alone -This becomes very important in places like Japan where landfill space is expected to be full in 2.5 years - Water intensiveness is also a major problem with concrete use, primarily for areas already experiencing water shortages in developing nations

__** Unsustainable Development and Implications: **__
- The implications of continuing rampant development and population growth across the globe are already vast but along with rampant use of concrete the impact is greatly compounded - Concrete is currently the second most used product on the planet second only to water: 10 billion tons of concrete are produced currently every year with this number rapidly increasing - 5% of global man made carbon dioxide emissions are caused by the use and production of cement and concrete - 2 billion metric tons of carbon dioxide emissions are estimated to be created due to the cement industry in 2010 and this value is expected to increase along with cement production to approximately 5 billion metric tons by 2050 - “In booming economies from Asia to Eastern Europe, cement is literally the glue of progress” (Rosenthal) - China currently makes and uses 45% of the world output of concrete, they currently are building new infrastructure at a rate equal to that of the entirety of the city of Houston every four weeks - The greenest current available technologies can reduce carbon dioxide emissions by only about 20%

**__ Solutions: __**
- General idea in “greening concrete” is to use as little Portland cement as possible by supplementing alternative bonding agents including those that result from industrial practices as well as replacing aggregate with recycled components to cut down on construction waste - Alternative for Portland cement include fly ash, ground granulated blast furnace slag (GGBFS) and condensed silica flume - These alternatives are all by-products of various industrial arenas including the coal, steel and semiconductor industries - These solutions aren't answers though, they typically are only capable of replacing a fraction of the Portland cement utilized and have some serious drawbacks for both design and cost - Recycled forms of concrete aggregate although not eliminating the hazards of cement can help eliminate solid waste problems associated with concrete - Calera corporation is developing process in which carbonate minerals are precipitated out of power plant flue gas and used as cement or aggregates in concrete (see link) - Cement sustainability initiative; industry led initiative to counteract effects of concrete (see link) - Novacem Corporation, eco-cement can absorb carbon dioxide from ambient air during hardening (see link) - Educational solutions to promote long term advances should also be explored such as incorporation of the impacts of concrete into concrete design classes for Civil Engineering majors - Stanford University's Civil Engineering Department offers a masters degree in Civil and Environmental Engineering with a concentration in sustainable design and construction

**Links**
Peer review journal article summarizing various current forms of “green” concrete: []

More specific information and properties of some “green” alternatives: []

Radical Solution to green concrete: []

Novacem corporation website; develops “green cement systems that will help combat global warming by locking atmospheric co2 into construction materials”: []

Cement sustainability industry led initiative: [] = =

= References = Bell, Michael Mayerfield. __An Invitation to Environmental Sociology.__ Thousand Oaks: Pine Forge Press, 2009. Fountain, Henry. __The New York Times.__ 30 March 2009. 9 February 2010 <[]>. Giussani, Bruno. __Business Week.__ 8 November 2006. 9 February 2010 <[]>. Hampton, Tudor Van. __Engineering News-Record.__ 2 February 2010. 9 February 2010 <[]>. __Industrial Air Quality and the Environment.__ 10 February 2010 <[]>. Meyer, C. "The greening of the concrete industy." __Cement and Concrete Composites__ (2009): 601-605. Rosenthal, Elisabeth. __The New York Times.__ 26 October 2007. 9 February 2010 <[]>. "The Cement Sustainability Initiative: our agenda for action." Industry Initiative. 2002. __Wikipedia .__ 9 February 2010. 10 February 2010 <[]>.