Challenge / Goal
Concrete is one of the world's most widely used building materials because it is durable, convenient and relatively inexpensive. Approximately 30 billion tonnes of concrete are used annually in the world for various types of construction and account for 6 percent of the entire earth's carbon dioxide emissions. Cement is the binder that holds together sand and stone in concrete. 95 percent of concrete's emissions come from the cement production itself.
In this way, it is incredibly urgent to find more environmentally friendly alternatives. But is it possible? Yes!
Together with Ecotopic, we are now testing using biochar and slag in concrete to reduce the climate footprint. It is a new and exciting area of research that opens up the possibility of making concrete completely climate-neutral, i.e. with zero carbon dioxide emissions.
Biochar, which is made from organic materials such as garden waste and wood, is a natural carbon sink because plants have already absorbed the carbon dioxide from the air. By mixing biochar in the concrete, it becomes denser and stronger. It also makes it possible to reduce emissions through less cement. At the same time, it binds carbon so that it does not end up in the atmosphere as carbon dioxide. The goal is to use biochar from recycled wood, i.e. wood from discarded wood products and used construction timber. Slag, which is a residual product from the metal industry, acts as a binder and can also replace some cement.
During the H22 City Expo on Drottninghögs torg, we tested four different types of concrete mixtures with biochar and slag in the foundations that hold the large crown in place. It gives us the opportunity to follow how the concrete reacts over time, for example by frost and rapid changes between hot and cold. All mixtures pass strength class C25 / 30.
Want to learn more about the lessons learned, financial details and results?