Like a green thread, this precast concrete staircase winds around the central column of the outdoor staircase of a primary school in Ghent, Belgium. The innovative escape route for students and teachers is part of a pilot project using alkali-activated concrete. This type of concrete significantly reduces the carbon footprint by using only 25% of the usual amount of clinker compared to conventional concrete. At the same time, it retains the benefits of concrete, such as exceptional load-bearing capacity and formability.