# An Investigation on the Synthesis of Alkali Activated Materials from Thermally Modified Clays
## 3 Results and Discussion
### Alkali Activated Mortars  
Mortar samples were produced and characterized to preliminarily assess the practical interest and industrial feasibility of the developed CRC binders. Fundamental properties evaluated in a fresh state included fresh density and workability. The workability of the mortars was investigated by the flow table test. The spread values were slightly reduced with the increment in the CRC content in the mix design (Table 6). However, all of the results are in line with the spread values used in regular hydraulic mortars (non-self-leveling/self-compacting) that typically lie in the range of 150-180 mm. Therefore, all mortars demonstrated adequate workability levels without the use of any additional additives and could meet the standard flowability requirements. The fresh density values were nearly constant, albeit slightly higher values were observed in the MR100 mortars. This effect was even more pronounced in the AD values at 28 days. The polymerization reaction seems to dictate the unit weight with progressive increases in fresh density and AD as the CRC dose rises (MR100, AD 28 dmax = 1.99 \(\pm\) 0.01 MPa). \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Code** & **SV (mm) \({}^{*}\)** & **FD (g/cm\({}^{3}\)) \({}^{*}\)** & **AD (g/cm\({}^{3}\)) \({}^{*}\)** & **EM (GPa) \({}^{*}\)** & **WA (\%) \({}^{*}\)** & **CI \({}^{*}\)** \\ \hline
**MR0** & 180 \(\pm\) 5 & 2.01 & 1.78 \(\pm\) 0.00 & 15.4 \(\pm\) 0.0 & 6.7 \(\pm\) 0.0 & 0.118 \(\pm\) 0.002 \\ \hline
**MR25** & 175 \(\pm\) 5 & 1.99 & 1.85 \(\pm\) 0.02 & 16.8 \(\pm\) 0.2 & 7.0 \(\pm\) 0.3 & 0.138 \(\pm\) 0.002 \\ \hline
**MR50** & 175 \(\pm\) 10 & 2.01 & 1.88 \(\pm\) 0.07 & 16.3 \(\pm\) 0.5 & 7.5 \(\pm\) 0.3 & 0.120 \(\pm\) 0.007 \\ \hline
**MR75** & 175 \(\pm\) 5 & 2.00 & 1.91 \(\pm\) 0.01 & 16.8 \(\pm\) 0.1 & 4.1 \(\pm\) 0.7 & 0.128 \(\pm\) 0.006 \\ \hline
**MR100** & 170 \(\pm\) 5 & 2.05 & 1.99 \(\pm\) 0.01 & 14.7 \(\pm\) 0.1 & 3.0 \(\pm\) 0.2 & 0.101 \(\pm\) 0.000 \\ \hline \hline \end{tabular}  
* Properties abbreviate as: SV—spread value; FD—fresh density; EM—elastic modulus; WA—water absorption; CP—capillarity index.  
\end{table} 
Table 6: The fresh and hardened properties of mortars produced with different dosages of local calcined clays at 28 days. Figure 10: A comparison between the XRD patterns of the binders synthesized with progressive replacement (0, 50, and 100%) of metakaolin by local calcined clay after 28 days of curing. As with the binders, CS and OP were the utmost important properties that must be investigated in AAM mortars. Figure 11 describes the relationship between the CS and OP levels in mortars produced with progressive dosages of CRC. The CS values decreased almost linearly as the CRC increased. Interestingly, a similar trend was not observed in the CRC binders (Figure 8), suggesting aggregate interference in the polymerization reactions/products and/or structural weaknesses located in the interfacial transition zones. The OP increased slightly with an increasing CRC up to 50 wt%, but beyond this threshold, considerable decreases were observed. The values for the WA and elastic modulus were greatly affected by pores and voids, following, in general, a pattern similar to that observed for OP (Table 6). The capillarity index values were found to be inconsistent and without any visible correlation to other properties. Therefore, the relationships between the density, porosity, CRC content, and strength development in the CRC mortars seem much more intricate with respect to the binders only, and effectively rely on a larger number of complex reactions and confounding variables. In Figure 11, the existence of three distinct zones is enunciated based on the MK replacement level. In zone 1, the increases in porosity seemed to be partially mitigated by the formation of slightly more resistant binders, while in zone 2, the exact opposite seemed to happen, but to a lesser extent.