Concrete is the most widely used construction material worldwide because of its versatility, strength, and durability. Applications range from roadways and dams to furniture and tiles. With proper manufacturing, reinforcement, and engineering design, concrete buildings can withstand earthquakes, explosions, and hurricanes, and the test of time. However, production of concrete—starting with the mining of limestone used to make portland cement and ending with the loading of concrete onto trucks—is responsible for about eight percent of the world’s carbon dioxide emissions as well as other sources of air pollution, including nitrogen oxide, sulfur oxide, and particulate matter finer than 10 and 2.5 micrometers (PM₁₀ and PM_2.5, respectively). See also: Air pollution; Carbon dioxide; Cement; Composite material; Concrete; Durability of Roman marine concrete; Nitrogen oxides; Reinforced concrete

Underside of a concrete roadway. (Credit: Gubin Yury/Shutterstock)

In spite of its considerable environmental footprint, concrete is here to stay. In the United States alone, the concrete industry is backed by strong trade associations, lobbying groups, and a 29-member congressional cement caucus. Nevertheless, co-beneficial improvements that affect both climate and human health can be made in concrete manufacturing to reduce both greenhouse-gas and air-pollutant emissions, according to University of California (UC), Davis researchers reporting in the journal Nature Climate Change (March 2020). But there are tradeoffs, because some efforts to reduce global greenhouse-gas emissions could increase local air pollution and damage human health. For example, the researchers found that carbon-capture and storage technologies could reduce greenhouse-gas emissions from concrete production by up to 28 percent. Yet unless clean energy were to power the technology, locally produced air pollutants could adversely affect human health. See also: Greenhouse effect

UC researchers offered several complementary concrete production strategies that could reduce both global greenhouse gas emissions and local air pollution. Among these strategies were using cleaner-burning fuel to produce cement, using renewable energy (solar or wind energy), and replacing part of the portland-cement materials with materials that required less energy and produced less carbon dioxide emissions. At present, the most energy-intensive part of concrete production is the cement-making process. Cleaner-burning fuels, such as natural gas or biofuels, that were used in the cement-making process showed the greatest co-benefits overall. At present, since replacing concrete with a “greener” alternative is both expensive and elusive, policy makers may have more effective strategies for reducing emissions from concrete production than materials scientists. See also: Energy sources; Materials science and engineering; Natural gas; Potential uses of biochar; Solar energy; Wind power