Fast Complexity: Additive Manufacturing for Prefabricated Concrete Slabs

Fast Complexity was developed as a collaboration between Digital Building Technologies (dbt.arch.ethz.c...) and Physical Chemistry of Building Materials from ETH Zurich (ethz.ch), with the support of NCCR DFAB (www.dfab.ch).
Concrete is responsible for 8% of our global carbon footprint. Now more than ever, it is imperative to use concrete more efficiently. With optimisation algorithms, we can design complex buildings that use less than half the amount of concrete, but we are limited by a fabrication technicality: the conventional timber formworks only allow us to build oversized monolithic boxes.
To tackle this problem, we propose a fully automatic method that combines the fabrication speed of concrete 3D printing and the geometric precision of reusable 3D printed formworks. We demonstrated this method with a highly optimised post-tensioned structural slab prototype.
To make this possible, we developed an innovative process that allows us to dynamically control the setting rate of the 3D printed concrete. This means we can extrude a fluid concrete that emulates the complex surface of the formwork perfectly, and a fast setting concrete that does not need any additional formwork for the upper structure.
This research was supported by the NCCR Digital Fabrication, funded by the Swiss National Science Foundation (NCCR Digital Fabrication Agreement 51NF40-141853).