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“Even when it’s gray, concrete is green.” According to National Ready Mixed Concrete Association (NRMCA), concrete has environmentally friendly features which make it the building material of choice for sustainability.
Concrete is the most widely used building material that has been used in various forms since the Roman times. The mixture of cement, aggregate, water, and chemical additives is a $35 billion industry in the United States alone. The operation and construction of buildings in the United States account for about 40 percent of all greenhouse gas emissions, often pointing to concrete as a major culprit.
However, a recent study from the Massachusetts Institute of Technology (MIT) asserts that certain measures can be taken to “drastically reduce and possibly eliminate” the carbon footprint of new concrete buildings and possibly even older ones as well.
The study looks at carbon emissions produced over the entire life-cycle of concrete buildings, from construction and use to demolition. The research was published by the MIT Concrete Sustainability Hub, which is funded by the cement and concrete industries. The two year study is believed to be the most detailed accounting ever taken on the life-cycle of buildings, focusing on sources of raw materials and their transportation.
Researchers found many areas of potential savings that would also cut emissions, such as expanding upon the thermal properties of concrete by incorporating it into the energy needs of buildings as insulation. Direct exposure to sunlight is also believed to allow heat storage during the winter and even at night.
The UN Intergovernmental Panel on Climate Change has identified that green building is the most cost-effective way to reduce greenhouse gas emissions. However, before real reductions take place, a reliable method for quantifying emissions needs to be established.
Cement and concrete companies hope to rise to that challenge by providing the MIT study in support of concrete as a sustainable building material. The goal of reducing life-cycle emissions from concrete buildings has been embraced by many in fact, leading The American Institute of Engineers to enter the 2030 challenge, an initiative to reduce building energy use.
Cities and other organizations have also joined the initiative, which calls for a 60 percent reduction of emissions immediately and a 100 percent reduction by 2030. If this is accomplished, concrete buildings will have no net energy consumption at all.
Falling in step with other multi process industries, the cement and concrete industry is going green through certification and taking more sustainable measures. The NRMCA has established a certification program for the multiple steps of cradle to grave construction, such as establishing concrete delivery professionals and sustainable concrete plant certifications.
Concrete has also been able to make the jump to being a sustainable choice through the development of alternative cements. Portland cement, invented in 1824, is the most commonly used cement throughout the world. The heating and mixing process to create this cement requires massive amounts of energy and emits alarming levels of carbon dioxide into the atmosphere.
To combat the high levels of greenhouse gases emitted as a byproduct of the concrete industry, Green innovators have invented cement substitutes such as fly ash, a waste product of coal combustion studied by MIT. Fly ash can be recycled to form a similar compound to Portland cement and displaces more than 25 percent of the cement used in traditional concrete.
Another break through of a more environmentally friendly concrete is pervious concrete, which as a 15-25 percent void structure that allows 3-8 gallons of water per minute to pass through each square foot. This allows rain water to drain back into the ground preventing run-off, an environmentally harmful process that has long been associated with pavement and cement.
To learn more about the green benefits of concrete, visit http://www.nrmca.org/greenconcrete/default.asp