Sustainable concrete: How the gray building material can become more climate-friendly

Wolfram Schmidt has a lot to tell. His pace of speech is correspondingly rapid. In less than an hour on the phone, he spans the range from cassava roots to high-rise buildings, from chemistry to logistics, from training to standardization. The gray material concrete, as becomes clear after a conversation with Schmidt at the latest, has many colorful facets. Loved by architects and suspected by the public, a new aspect is now pushing into public awareness: its carbon footprint.

After water, concrete is the most widely used material by humans. It consists primarily of gravel and sand held together by cement. Its production alone accounts for a whopping six to ten percent of global CO, depending on the source₂-Emissions responsible. Trend: presumably rising, because emerging countries in particular have a lot of catching up to do. “80 percent of the buildings that will be in Africa in 2050 have not yet been built,” says Schmidt. “Africa could be a pioneer in green building.”

He himself works at the Federal Institute for Materials Testing (BAM) with unconventional ideas to make concrete more climate-friendly. The bad news is: You always have to turn several adjusting screws at the same time, because the CO₂Emissions occur in different ways. The good one: There are plenty of approaches to improve the carbon footprint anyway. They bring color to the gray world of concrete.