BY MEG CALKINS, FASLA
New technologies can reduce the environmental footprint of the most-used construction material.
FROM THE JULY 2017 ISSUE OF LANDSCAPE ARCHITECTURE MAGAZINE.
Concrete in the 21st century promises to be a more sustainable material, and given the nine billion metric tons used globally each year, it must be. Portland cement, the binding agent in ordinary concrete, has a very high carbon footprint, resulting in just under one ton of carbon dioxide (CO2) released for every ton of cement produced. With 4.2 billion metric tons of the binder used each year worldwide, cement production is responsible for nearly 8 percent of total global carbon emissions. The high lime content of ordinary portland cement contributes about two-thirds of cement?s CO2 impact through the process of limestone calcination. The other one-third of CO2 released is from combustion of fossil fuels. Technologies to improve the carbon footprint of concrete are currently in the early stages of development, but some, including carbon sequestration in concrete and substantial reductions of cement using energetically modified cement, are now commercially available. Concrete surface products for paving and walls to scrub air pollution, as well as new self-healing concrete products, are also worth investigating. We have heard about some of these innovations for a decade or more in the research community, but many are finally being brought to market?some more quickly than others. Europe is ahead of...