Investigation on Structural Build-Up of 3D Printable Foam-Concrete (2020-07)¶

Over the last decade the use of foam concrete in the construction industry has become popular due to its high thermal and acoustic insulation capacity in combination with sufficient strength characteristics. The use of foam concrete in 3D printing (3D Foam Concrete Printing) is a perspective approach which should enable automated freeform construction without formwork and at the same time would contribute to sustainability and energy efficiency of the structures. Since 3D-printing requires very specific rheological properties of foam concrete in its fresh state, a systematic research on this subject is needed. For this purpose, foam concrete mixtures containing more than 35 vol% protein-based foam and fresh density of approx. 1200 kg/m3 were developed and investigated with respect to their suitability for 3D printing by extrusion-based selective material deposition. Constant shear rate rheometer tests were performed to determine static yield stress and critical strain at flow onset at concrete ages of 30 min to 150 min, the time interval specifically relevant for the 3D printing process. Finally, the estimation of structural build-up was verified by manufacturing 800 mm long foam concrete walls until their collapse.