Research Summary Report A02

Particle-Bed 3D Printing by Selective Cement Paste Intrusion (SPI) – Particle Surface Functionalisation, Particle Synthesis and Integration of WAAM Reinforcement

[26.02.2021]

Hamilton, Leigh Duncan; Researcher, leigh-duncan.hamilton@tu-bs.de

Breitung-Faes, Sandra; Leading Researcher, s.breitung@tu-bs.de

Kwade, Arno; PL, a.kwade@tu-bs.de

All: TU Braunschweig, Institute for Particle Technology (iPAT)

Selective cement paste intrusion (SPI) is an additive manufacturing method where aggregate particles are spread in small layers, followed by the local intrusion of the cement paste into the aggregate layers. These steps are repeated layer-by-layer and the consequent hardening forms the structure. In comparison to other AM processes, the necessity of support structures for cantilevers is redundant for SPI. In addition, research to date has shown that SPI-made components closely acquire isotropic compressive strength (>70 MPa), reliable shape accuracy as well as high durability.

Whilst the aforementioned advantages are promising for future industrial implementation, the SPI process is in need of a reinforcement mechanism in order to perform a scale-up, and thus, produce structural concrete elements. Hence, the goal of the project A02 is the implementation of Wire and Arc Additive Manufacturing (WAAM) as a means of simultaneously printing the reinforcement during SPI. A successful implementation of WAAM would provide the production of reinforced concrete structures in accordance with the principle of “form follows force”, leading to economically and ecologically viable components.

The combination of SPI and WAAM is accompanied by obstacles that must be overcome in order to ensure the collaborated functionality. One major challenge occurs from the propagated thermal load of WAAM (approx. 1600 °C), which has negative effects on the paste rheology and resulting concrete strength. Therefore, the overall goal is to minimise heat propagation into the particle bed [1].