## 4 Applicability of Concept
### Outlook to Envisaged Investigations  
In order to make the AMoRC process ready for practical application on construction sites and in prefabrication plants, future works are planned addressing, on the one hand, the investigation of mechanical properties of the additively produced composite material and, on the other hand, the combination of concrete extrusion and stud welding process within a hybrid print head.  
The aim is to setup a fully automated high-speed process suitable for production of members with wall thicknesses which are common in reinforced concrete construction, and reinforcement  
Figure 4: Demonstrator produced with the AMoRC process (**a**), concrete placement with twin nozzle (**b**).  
Figure 5: Spread diameter of H\(\ddot{\text{a}}\)germann flow table test with increasing time. The dotted line shows values after 15 shocks and the continuous line without shocks.  
arrangements with at least one reinforcement layer per outer surface. For this purpose, fork-shaped, multi-nozzle extrusion heads for layer thicknesses of 50-100 mm and filament widths of 180 to 240 mm are to be developed (Figure 6a). An important objective is to ensure merging of concrete fed from individual nozzles within one continuous filament. In this context, the spacing of adjoining nozzles plays a crucial role. Preliminary investigations with the existing nozzle geometries (Figure 4) and feed rates show that defects can occur near the reinforcement if the nozzle spacing is chosen too large. During demonstrator production, clear defects were observed if the spacing of nozzles exceeded twice the reinforcement diameter (Figure 6b). In this context it is important to highlight that typical wall reinforcement usually has horizontal and vertical reinforcement that needs to pass between the nozzle gaps. If these bars are of the same diameter, then the gap needs to be more than two times bar diameter. There are different ways to face this aspect; for instance, using flexible nozzles with small gap spacing which allow the bars to squeeze through or implementing print heads with separate gaps for horizontal and vertical reinforcement. In addition, there are encouraging results, that defects reduce significantly when operating at higher feed rates. Besides a detailed investigation of these aspects, investigations into the bond properties of encased rebars are planned for both the horizontal and vertical reinforcement direction.  
Furthermore, the combination of the printhead with additional features to actively control fresh concrete properties and devices to ensure adequate concrete interface quality will be investigated.  
In the field of welding technology, systematic research into modified arc stud welding for joining reinforcement is planned. In addition to assessing the quality of the material connection (hardening of steel, geometric parameters), the development of various possibilities of joining bars of different diameters at any desired angles in space play an important role. To evaluate the material properties of the steel, tensile and bending tests, macrosections and hardness tests of the joining zones are carried out. Finally, the methods developed for concrete extrusion and steel joining are combined into a simultaneously running hybrid process.