The formwork is a double layer of fusible fabric (creating sort of a pillow) with the concrete poured in-between the layers.
Building Matters The formwork is a double layer of fusible fabric (creating sort of a pillow) with the concrete poured in-between the layers.

Some interesting formwork was used by University at Buffalo architectural student Allison Adderley to create an unusual concrete element. The formwork is a double layer of fusible fabric (creating a pillow) with the concrete poured in-between the layers. This installation in the Buffalo Grain Elevators was suspended with cables. As the concrete heated up it caused a chemical reaction in the fabric which made it rigid and allowed it to absorb into the concrete. The absorbed fabric acted as formwork as well as an additional layer of reinforcement. The final installation had 3200 pounds of concrete poured and suspended above the ground.