3D printing of sustainable infrastructure using rapid-set clay concrete with biobased additives

The exponential growth of the human population has led to a global housing crisis. To solve this problem, additive manufacturing (AM), also known as 3D printing, has become widely used for on-demand infrastructure construction. While 3D printing offers faster build times and greater design flexibility, it is limited by slow-setting concrete, interruptions to install supports, and the massive environmental impact of cement, which accounts for around 8% of global CO₂ emissions. This work introduces a 3D printable, clay-based construction material that provides structural properties comparable to concrete yet cures immediately after printing. Thermally initiated frontal polymerization of an acrylamide-based binder enables setting during extrusion, allowing layers to be printed consecutively. While 3D printed concrete is typically comprised of 30–60% cement binder, our material contains 70–80 wt.% biobased materials, which can be obtained in situ. The printed material reaches buildable strengths of 3 MPa immediately after printing, enabling construction of multilayer walls and freestanding overhangs such as framing or roofs. Furthermore, the material surpasses 17 MPa, the strength required of residential structural concrete, in just 3 days, whereas traditional concrete can take up to 28 days. The methods developed in this work show great promise for the rapid, on-demand fabrication of sustainable infrastructure.