Additive Manufacturing in Construction
AMC TRR 277

Research Summary Report of A05

Integration of Individualized Prefabricated Fibre Reinforcement in Additive Manufacturing with Concrete

[02.11.2022]

Gantner, Stefan; Scientific Researcher, stefan.gantner@tu-bs.de,

TU Braunschweig, Institute of Structural Design (ITE)

 

Summary

Cement-based additive manufacturing techniques need to be enhanced by the ability of integrating reinforcement, in order to fulfil requirements of construction. This project focuses on non-metallic continuous fibre reinforcement, which is not only corrosion resistant but also flexible in handling. Instead of bending and welding, glass or carbon fibre rovings can be processed by winding onto a support structure.

Based on three fundamental AM-principles, namely material jetting and extrusion, as well as particle bed printing, a set of winding concepts for integrating reinforcement has been developed. Within a holistic framework all relevant aspects from fabrication constraints to the scope of applications are considered. The interaction of printing process and reinforcement integration is already playing an important role in the conceptual design. If the reinforcement is integrated into additive manufacturing in a subordinate step, this leads to different shaping possibilities than if a fibre structure is preproduced serving as support for subsequent concreting.

Meanwhile new concepts like the fabrication of double-curved reinforcements mats on a specially designed pin grid are being tested, the three main concepts that emerged from the initial research phase are being investigated more in-depth. Regardless of the initial difficulties, the integration of prefabricated fibre structures into particle bed printed elements has been established successfully and is currently being analysed for bond behaviour.

Furthermore, Shotcrete 3D Printing (SC3DP) on an individualised fibre mesh with a mobile formwork shield on the backside – “Shield Printing” in short – was examined for possible influences from the manufacturing process. Like this, the quality and repeatability in the fabrication of thin additively manufactured and reinforced elements could be improved.

The most robust and elaborate technique from this project so far is Core Winding Reinforcement (CWR). Here, the bond quality within the resulting composites is object of ongoing studies (see Figure 1).

 

Fig. 1: A Shotcrete 3D printed beam specimen with robotically integrated glass fibre reinforcement by means of Core Winding is subjected to a four-point flexural test.