## 3 Results and Discussion  
The thermal activation of many clayey materials within the range of 600 \({}^{\circ}\)C to 900 \({}^{\circ}\)C causes the total or partial decomposition of the crystalline network, due to dehydrodxylation, passing through a transition state or phase with high reactivity. The clay is found in its most reactive state when calcination leads to a loss of hydroxyls and results in a collapsed and disordered clayey structure. The calcination temperature for K that produces the active state of MK is found within the 600 \({}^{\circ}\)C/800 \({}^{\circ}\)C interval [21; 32], where the quantity and the type of the amorphous phase might have influenced the pozzolan activity. In both cases, wastes were thermally activated at 600 \({}^{\circ}\)C in an oven for over 2 h.  
The silica-aluminous nature of the chemical composition of the CW should be highlighted, in which the sum of both oxides was over 70% of the total (Table 1). The presence of trace elements was also detected, such as Cr (180 ppm), V (141 ppm), Ni (53 ppm), Mo (21 ppm), Pb (4 ppm), Zn (25 ppm) As (2 ppm), and Co (22 ppm), in addition to chlorides (82 ppm). The crystalline mineralogical composition of CW was principally composed of quartz (37%), phyllosilicates (micas 25%, illite 52% and kaolinite 14%), calcite (17%), dolomite (5%) and potassium feldspar (2%) (Figure 1). \begin{table}
\begin{tabular}{c c c c c c} \hline
**Oxide (\%)** & **PS** & **APS** & **CW** & **ACW** & **OPC** \\ \hline SiO\({}_{2}\) & 10.69 & 20.24 & 49.79 & 56.63 & 20.16 \\ Al\({}_{2}\)O\({}_{3}\) & 6.74 & 3.11 & 21.77 & 25.29 & 4.36 \\ Fe\({}_{2}\)O\({}_{3}\) & 0.41 & 0.52 & 4.07 & 4.64 & 2.52 \\ CaO & 24.15 & 36.39 & 3.84 & 4.20 & 63.41 \\ MgO & 0.96 & 2.15 & 0.64 & 0.77 & 2.21 \\ SO\({}_{3}\) & 0.30 & 0.28 & 0.27 & 0.27 & 3.57 \\ K\({}_{2}\)O & 0.22 & 0.34 & 2.74 & 3.09 & 0.91 \\ Na\({}_{2}\)O & 0.24 & 0.08 & 0.13 & 0.17 & 0.35 \\ TiO\({}_{2}\) & 0.21 & 0.24 & 1.07 & 1.17 & 0.21 \\ P\({}_{2}\)O\({}_{5}\) & 0.16 & 0.17 & 0.13 & 0.14 & 0.14 \\ LOI & 55.71 & 26.24 & 15.18 & 3.09 & 1.99 \\ \hline \end{tabular}
\end{table} 
Table 1: The chemical composition of the studied materials via X-ray Fluorescence (XRF). The thermically ACW [32] maintained their silica-aluminous nature, the sum of their principal oxides SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\) and Fe\({}_{2}\)O\({}_{3}\) amounting to 80.19%, which is a higher value than the 70% that is specified for the standardized pozzolans of the same nature (fly ash and calcined natural pozzolan) in the American standard (ASTM 618-12) (Table 1). The presence of Cr (228 ppm), Ni (43 ppm), Pb (5 ppm) and Zn (46 ppm) was also detected as trace elements. The main phases identified by XRD were quartz (54%), hematite (3%), phyllosilicates (20%), calcite (22%) and reflections at 2.43 A (36.98\({}^{\circ}\) 26) and 2.85 A (31.38\({}^{\circ}\) 20) due to the spinel phase (1%), the formation of which is related to the warming of clayey minerals containing a high quantity of aluminum [33] (Figure 1). The results of the chemical composition (Table 1) of PS show that these wastes presented a silicate-aluminum-calcite nature, in which the three oxides amounted to 42%. The loss on calcination at 950 \({}^{\circ}\)C during 1 h in an electric furnace (loss on ignition (LOI) = 55.71%) was very high due to the presence of calcite and organic material. The main crystalline mineralogical compounds of the PS sample were calcite (35%), dolomite (1%), kaolinite (21%), as well as other minerals such as phyllosilicates (2%), mica (7%) and quartz (6%), while the rest was formed of organic matter (Figure 2). The chemical composition of this APS presents silica, aluminum and lime as its principal oxides, a composition that is maintained with regard to its original material, PS, the sum of its three oxides (CaO + SiO\({}_{2}\) + Al\({}_{2}\)O\({}_{3}\)) amounting to 69.3%, while the sum of SiO\({}_{2}\) + Al\({}_{2}\)O\({}_{3}\) + Fe\({}_{2}\)O\({}_{3}\) is only 61.5% (Table 1).