# Development of Cementitious Mortars for Aerial Additive Manufacturing
## 3 Results  
### Workability and Autonomous Deposition Device Performance  
The power requirements for the deposition device are shown in Table 3 with an empty syringe in comparison with the mixes. As the deposition device would be powered by a UAV in flight, the less power required for material extrusion the better, as power requirements for extrusion have to be within the capabilities of the UAV without compromising power capacity for the primary function of flight. To operate the deposition device with cement paste mix \(A\), the current required was 61 mA \(\pm\) 5 mA and it took 60 s to draw up, or extrude, 10 mL of cementitious paste. This increased to 104 s per 10 mL for Mix \(D\), which yielded a mean current during draw-up and deposition of 84 mA \(\pm\) 15 mA. An 8 mm diameter nozzle produced a mean flow velocity out of the syringe of 3.16 mm/s and resulted in a 200 mm line of material being extruded per 10 mL of material in the syringe. This was sufficient to produce a 50 mm diameter circular printed layer with a 157 mm circumference, theoretically requiring 7.9 mL of material to complete a layer. Therefore, to produce one circular layer it took 79% of the time required to process 10 mL (Table 3, column 3). The 78.5 s per layer velocity of the robotic arm ensured that it was not travelling too quickly for deposition device extrusion and enabled the printing of a consistent bead of material.  
The deposition device comfortably processed 20 mL of material for mixes \(A\) and \(C\). Mixes \(B\), \(D\) and \(E\) were more challenging, with the device having difficulty in drawing up 10 mL of mixes \(B\) and \(D\). Mix \(D\) required 45% more power to process the material than mix \(C\), which in turn required only slightly more power to process than an empty syringe.  
Table 4 displays the workability and buildability classification for each mix along with mix density and the number of layers the syringe device could process within the two-hour open time period. The classifications reflect the performance of the material during processing. For example, mix \(A\) deformed irreparably upon the deposition of the sixth layer (as shown in Figure 3), hence a poor buildability rating, whilst mixes \(B\) and \(D\) performed well in terms of buildability, but possessed poor workability as eight layers could not be printed due to the syringe device being unable to draw-up the mortar after 45 min (mix \(D\)) and 60 min (mix \(B\)). Table 4 also reveals the least workable mixes of \(B\) and \(D\) as possessing the highest density.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Mix** & **Current** & **Time** & **Energy** & **Power** \\  & **(mA)** & **(s)** & **(Joules)** & **(Watts)** \\ \hline Empty & 58 & 58 & 20.0 & 0.345 \\ \(A\) & 61 & 60 & 21.8 & 0.363 \\ \(B\) & 79 & 76 & 35.8 & 0.470 \\ \(C\) & 58 & 62 & 21.4 & 0.345 \\ \(D\) & 84 & 104 & 52.0 & 0.500 \\ \(E\) & 74 & 61 & 26.9 & 0.440 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Performance of the deposition device showing power requirements for mixes \(A\)–\(E\) in comparison to an empty syringe. The time and energy transferred values refer to 10 mL movement of the plunger in the syringe.