Don't+Worry?+Presentation

__**Background:**__
- Concrete is potentially environmentally friendly (it’s primarily made from rocks), the only real problem with concrete is that it utilizes Portland cement which is not particularly environmentally friendly - Concrete is a very important building material; not something easily replaced by other materials and it offers many construction advantages including excellent mechanical and durability properties, ability to be molded into any desired shape as well as being fairly fire resistant and generally affordable and available - Concrete can be engineered effectively to meet any specific performance specifications more so than any other material currently used in construction

__ Air pollution and Global Warming: __
- Production of one ton of Portland cement releases approximately one ton of carbon dioxide into the atmosphere - 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 which constitutes 7 to 15 percent of the concrete weight, this amount of energy is equivalent to 345 lbs of coal per ton of cement - 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 - Energy used to create concrete is comparable to the energy intensive methods for creating steel and wood but this reaction describe above greatly increases its air pollution and global warming impact - 50% of the Carbon dioxide emissions created in concrete production are chemical related, 40% are attributed to fuel and 10% to transportation and electricity needs

__** Other Environmental Concerns: **__
- Concrete production process causes environmental impacts at all stages from damage to countryside due to quarrying for limestone 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 also generated each year in the United States alone - In places like Japan were landfill space is expected to be full in 2.5 more years this additional waste has nowhere to go - Water intensiveness is also a major problem with concrete use primarily for areas already experiencing water shortages, water typically can account for approximately 7 to 15% of the initial weight when the concrete is formed

__** Unsustainable Development and Implications: **__
- Unsustainable development in the sense of quantity in itself is a large problem as we continue to destroy natural landscapes and over inhabit out world and continue to consume more products; stretching the earth’s resources to its limits - The implications of continuing this rampant development along with this environmentally unfriendly construction material will even further increase its impacts - 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 numbers 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 increases 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, the currently are building new infrastructure at a rate equal to that of the entirety of the city of Houston every four weeks - Ukraine has experienced a doubling of concrete usage nearly every four years - 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 areas including the coal, steel and semiconductor industries and they have become available in modern era as clean air regulations have forced installation of scrubbers to trap these fine particles - Most of these solutions are generally and similar in cost or better strength and durability - Problems with fly ash are a slow rate of strength development and inconsistent chemical properties from plant to plant - These solutions aren't answers though, they typically only are capable or replacing a fraction of the Portland cement utilized - Recycled forms of concrete aggregate although not eliminating the hazards of cement can help eliminate solid waste problems associated with concrete - Problems with recycling concrete waste directly is contaminants such as plaster, soil, wood, gypsum, asphalt and rubber and excess cement mortar causes material to absorb more water resulting in lower densities which reduces strength - 5% to 24% reductions in strengths have been seen for recycled coarse aggregate and 15 to 40% reductions for both fine and coarse recycled aggregate - Increasing cost of disposal and cost of transportation may cause RCA to become more feasible - Post-consumer glass and old tires also are possible aggregate replacement alternatives being explored - 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 sustainability design and construction - Overall some of these ideas have penetrated into industry especially in Europe at an accelerating rate but the concrete industry has a huge environmental footprint to attempt to counteract

**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 .