# Development of Cementitious Mortars for Aerial Additive Manufacturing
## 3 Results
### Rheology, Fourier Transform Infrared Spectroscopy (FTIR) and Calorimetry  
Figure 4a illustrates the Complex modulus G* of the mortar mixes along with the number of layers printed by the deposition device on the secondary axis. Elastic deformation was dominant in all mixes, confirming the mixes behaved in a more solid-like than liquid-like manner. The mixes are sequenced with \(G^{*}\) in ascending order and a relationship between G* and the number of layers printed can be observed. The fibrous Mix \(D\) was \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Mix** & **Density (kg/m\({}^{3}\))** & **Workability** & **Buildability** & **Layers Printed** \\ \hline \(A\) & 1978 & very good & poor & 6 \\ \(B\) & 2073 & poor & good & 4 \\ \(C\) & 1753 & very good & good & 8 \\ \(D\) & 2113 & poor & good & 3 \\ \(E\) & 1871 & good & good & 8 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Workability (the ability of the material to be processed by the deposition device) and buildability (quality of defined circular layers extruded without excessive deformation) visual classification for mixes \(A\)–\(E\), with the fresh mix density shown and number of layers the syringe device could draw up and deposit. Figure 3: The 50 mm diameter circular layers of the extruded mixes: \(A\) (cement paste), \(B\) (the introduction of fine aggregate), \(C\) (polyol resin), \(D\) (polpropylene fibres) and \(E\) (LimeX70). Refer to Table 2 for the full mix constituent proportions and Table 4 for mix densities. the most challenging mix for the syringe device to extrude due to the highest complex modulus, while mixes \(A\) (the cement paste) and \(C\) (with the polyol resin) possessed the lowest \(G^{*}\) and were the most workable mixes for the syringe device. The rheological suitability of the mixes is suggested by the number of layers printed in Figure 4a. This is further depicted in Figure 4b to show the range of \(G^{*}\) favourable for a mortar mix possessing a good workability-buildability balance. Mort  
Figure 4: Rheology, FTIR and Calorimetry results. (**a**) Complex modulus \(G^{*}\) for mortar mixes \(A\)–\(E\), averaged over the open time of two hours. Mixes are ordered left to right in order of ascending \(G^{*}\). \(G^{*}\) significantly dominated over \(G^{*}\) for all mixes. The number of layers printed is also indicated for the mixes. (**b**) The relationship between Complex modulus \(G^{*}\) and the number of layers printed by the deposition device. The ‘suitable mix’ \(G^{*}\) range shows a suitable workability-buildability balance. (**c**) The relationship between Complex modulus \(G^{*}\), the power required to process the mixes and time taken to draw up 10 mL of mixes \(A\)–\(E\). (**d**) FTIR spectrum of the polyol resin used in this study, Isothane’s Reprocell 500 (used in Mix \(C\)) to demonstrate the presence of hydroxyl groups. (**e**) Calorimetry experiments for mixes \(A\)–\(E\) depicting the energy transferred per gram of material and (**f**) Calorimetry results illustrating the rate of heat evolution per hour. \(G^{*}\) of between 3 and 6 MPa can be considered suitable for the deposition device used in this study. The relationship of Complex modulus \(G^{*}\) with both the power required and time taken for the autonomous syringe device to draw-up 10 mL of mixed material is shown in Figure 4c. The positive correlation between \(G^{*}\) and time on the scatter graph can be observed as linear while \(G^{*}\) and power can be observed as non-linear. As can be seen in the FTIR spectrum (Figure 4d), the characteristic bands of hydroxyl and carbonyl groups are observed in the 3430 \({}^{-1}\) and 1726 cm\({}^{-1}\) regions, respectively. The bands in the range from 2800 \({}^{-1}\) to 3000 \({}^{-1}\) are associated with C-H asymmetrical and symmetrical stretching vibrations [35]. The band at 1075 \({}^{-1}\) indicates the stretching of C-O [36].