Big cities are already in a period of unprecedented “hyper-growth” and the United Nations predicts that the equivalent of between five and seven cities the size of New York will need to be built each year between now and 2050 to accommodate a growing global population predicted to surge past 9 billion by mid-century.
Concrete, as the most used man-made material on the planet, will play an important role in shaping these current and future cities, but with pervasive use of the material comes a high environmental cost. Concrete production accounts for more than 5 percent of annual emissions of carbon dioxide, a heat-trapping greenhouse gas, and it also uses a lot of water resources.
“These are significant environmental issues, but they receive little attention in broader discussions of climate action,” says Roland Pellenq, senior research scientist with the MIT Concrete Sustainability Hub (CSHub) and head of the joint MIT-CNRS MultiScale Material Science for Energy and Environment (MSE2).
Pellenq, along with Georgetown University’s Emanuela Del Gado and Marlene Towns; William Updike of the U.S. Department of Energy and Environment; and Jason Turner of Verdant Innovation, organized a symposium held this month at Georgetown University. The event convened scientists and researchers, municipal government officials, and experts from industry and sustainability fields from across the country. CSHub Faculty Director Professor Franz-Josef Ulm and Executive Director Jeremy Gregory were among the speakers and panelists on the schedule.
“City leaders are challenged to focus greater attention and resources on mitigating the negative effects of indispensable products like concrete, while at the same time supporting smart city infrastructure growth,” says Pellenq. The symposium, which was funded by the Georgetown Environmental Impact Initiative (GEI), was called with this in mind and, specifically, with the goal of discussing and fast tracking “shared directions for the world’s biggest cities to reduce the environmental impact [of concrete] in view of growing population and infrastructure-driven demand for concrete use.”
When discussing sustainability and concrete, says Del Gado, a theoretical physicist and Provost's Distinguished Associate Professor of Physics at Georgetown, “it is of crucial importance to discuss strategies for sustainability of cities in terms of infrastructure building and materials used.” This was a theme that carried through the symposium right from the opening address by Washington, D.C., Mayor Muriel Bowser who highlighted the leadership role cities can assume when it comes to driving home the value of environmental protection while also implementing effective, affordable and durable practices. Another speaker, Brendan Shane from the group C40 Cities, discussed the power that cities can have on encouraging positive environmental practices through coordinated efforts.
Del Gado recently visited the MIT Campus for the C.C. Mei Distinguished Speakers Series, presented by MIT Civil and Environmental Engineering, where she gave a lecture on sustainable cement. About the symposium, she said she was struck by how “excited and motivated” participants were “when they realized that their counterpart, the people they needed to talk to…to make things happen, was actually there, ready to discuss, ask questions, provide answers.”
Jason Turner, one of the symposium co-organizers, noted that one of the things participants learned was the “real structural disadvantages” that low-income residents, and particularly minorities, face when it comes to climate effects in big cities. “Understanding the real costs that result from the choices we make for materials on our services has a major impact," he says, later adding, “Having the direct participation of industry in the conversation breaks down barriers and accelerates positive change in outcomes for cities.”
According to organizers, the symposium helped to identify three directions that can help define strategies for mitigating concrete’s environmental impact. The first is addressing and redefining standards, based on performances, to make sure that they actually help improve concrete sustainability, including durability. The second is coordinating efforts by cities and industrial players in defining effective policies. The third is having researchers and technological innovators work together to quantify carbon costs of concrete in different contexts and identify a portfolio of solutions.
“Recognition that research, technological innovation and concerted policy efforts are needed in this area can make a big difference in both the short term and the long term for the planet and for sustainability,” says Del Gado.
The MIT Concrete Sustainability Hub (CSHub) conducts research to reduce the impact of concrete production and use, and also develops tools to support infrastructure decisions with economic, environmental and other factors, such as hazard resistance, in mind. The CSHub will host a free, public webinar on an approach to the life cycle cost analysis of buildings incorporating costs due to hazards on Thursday, May 25.
The Hub was established in 2009 with funding from the Ready Mixed Concrete (RMC) Research & Education Foundation and the Portland Cement Association (PCA).