## 3 Test Results and Discussion
### Binder Properties
#### 3.1.6 Mortar Hydrate Mineralogy and Content  
Results of the XRD analysis for the PC mortar and those of LC\({}^{3}\) (BFN, MFN, EXW) are shown in Table 8 (see Figure 7 for the XRD patterns). The two main peaks at 24.2\({}^{\circ}\) 20 and 31\({}^{\circ}\) 20 represent quartz (SiO\({}_{2}\)), and they mainly originate from the sand content of the specimens. From the mixture design, the estimate of the sand content is about 60%, which is obtained for the OPC mortar from the XRD results. A higher percentage of quartz in the clay samples (63-72%) implies that some sand impurities were in the samples. Ettringite is formed in LC\({}^{3}\) mortars as part of the pozzolanic reactions due to the limestone reacting with additional alumina. It can be observed from Table 8 that the ettringite content seems to not be influenced by the kaolinite content of the clay; this has also been confirmed by another study [6]. It is noted that the ettringite content in the control is zero, which can be due to the low amount of aluminate in the Portland cement, detected as 1.26% in Table 5, unlike 10% common content in OPC. This could have led to small amounts of ettringite formed being converted to monosulphate.  
The amorphous phases in Table 8 include metakaolin and calcium silicate hydrates. As noted earlier, the combined formation of extra CASH, ettringite, and carbo-aluminates in the pozzolanic reaction refines the microstructure densification and strength. In addition, the consumption of portlandite signifies the pozzolanicity of the clay samples, which can be directly proportional to the kaolinite content. These results are confirmed later in this study from the strength results where EXW LC\({}^{3}\) mortar has better relative strength.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Elements** & **O** & **Mg** & **Al** & **Si** & **Cl** & **K** & **Fe** \\ \hline EXW & 72.208 & 0.184 & 8.58 & 14.354 & 0.272 & 1.904 & 1.01 \\ BFN & 73.4275 & 0 & 10.475 & 15.4175 & 0.22 & 0.4175 & 0 \\ MFN & 65.3775 & 0.34 & 8.055 & 13.2325 & 0.05 & 0.5925 & 0.66 \\ \hline \hline \end{tabular}
\end{table}
Table 7: EDS average elemental results from 28 spectra each.  
Figure 6: SEM images of limestone powder and the EDS analysis from the spectrum (the insert table is the average of 12 other spectra).  
Assuming that the content of the calcite in the OPC mortar emanates from the extender in Suretech CEM II/A-L 52.5N, then BFN, MFN, and EXW mortars can be said to contain 2.45%, 1.95%, and 2.55% calcite, which is less than about 4% of limestone originally in the mixture. This suggests that the limestone is being consumed for hydration, a physico-chemical activity from the extra nucleation sites provided by the fine particles of the limestone and the formation of mono-carboaluminates [13; 30]. This result supports the better 3D void microstructure later obtained for the MFN sample with the least calcite content. The consumption of portlandite for the calcined clays is proportional to the kaolinite content. MFN, BFN, and EXW with 29.5%, 32.8%, and 41.6% contents had 0.8%, 0.6%, and 0.5% of portlandite, respectively, signifying that higher kaolinite content guarantees better pozzolanic activity.