## 3 Results and Discussion
### Matric Suction Determined Using the Filter Paper Method
#### 3.1.1 Matric Suction of Compacted Clay with Varying Initial Void Ratios
The cracks that formed were due to the sudden re-saturation of the compacted soil, wherein the top portion of the specimen expanded while the bottom layers were still at a smaller dimension compared to the re-saturated portion, which created friction between the layers that produced the cracks (Kurur  
Figure 8: Oven-dried (**a**) CCL and (**b**) CL at the end of the 1 st wet–dry cycle. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Source** & **Sum of Squares** & **Degrees of Freedom** & **Mean Square** & **F-Value** & \(p\)**-Value** & \\ \hline Model & 418.17 & 11 & 38.02 & 144.32 & \textless{}0.0001 & Significant \\ Moisture content & 371.46 & 1 & 371.46 & 1410.20 & \textless{}0.0001 & Significant \\ Void ratio & 0.19 & 1 & 0.19 & 0.72 & 0.3990 & Insignificant \\ Cycle & 3.74 & 2 & 1.87 & 7.11 & 0.0012 & Significant \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Analysis of variance of CCL and CL matric suction. The SEM images, with a magnification of \(\times\)1000, of the loose clay, compacted specimen before the wet-dry cycle, and compacted specimen after exposure to three wet-dry cycles are shown in Figures 13 and 14. It can be observed that compaction reduces intergranular voids present in the uncompacted condition. Moreover, after the specimens were subjected to wet-dry cycles, the intergranular voids increased compared to the compacted specimen before the wet-dry cycles. More aggregates that were uniform in size were also observed after the specimen underwent wet-dry cycles. Moreover, the edges of the particles were more defined after undergoing wet-dry cycles. Thus, the cyclic wetting and drying deteriorated the microstructure of the specimen and increased the number of pores, which was a significant factor that affected the decrease in matric suction. The wet-dry cycles ruptured the plate structure of the compacted specimen, which resulted in an increase in the amount of aggregate, a decrease in the aggregate size of the specimen, an increase in specific areas of the soil particles, and, in turn, a looser, more porous compacted specimen [7; 42]. Moreover, aggregate contours and increased porosity were more apparent. Figure 11: Saturated (**a**) CCL and (**b**) CL at the start of the 3 rd wet–dry cycle. Figure 12: Air-dried (**a**) CCL and (**b**) CL at the level 7 moisture content of the 3 rd wet–dry cycle. Figure 9: Saturated (**a**) CCL and (**b**) CL at the start of the 2 nd wet–dry cycle. Reduction in connectivity and a change from face-to-face contact to point contact that was observed in SEM images of the specimen that underwent wet-dry cycles were also effects of the deterioration caused by the cyclic wetting and drying [7]. The change in microstructure indicates that the water dissolved the cementing matters during the wet-dry cycle, which caused small- and medium-sized pores to develop into macropores [42]. In addition, according to [PERSON] et al. [43], the expansion of kaolinite leads to an increase in pores where water enters the soil, resulting in disintegration. Quadratic regression models were developed to predict the matric suction. The quadratic models of the responses and the factors are shown in Figure 15. The quadratic regression models for a range of moisture content and initial void ratio are expressed in Equations (8)-(10). The high coefficient of determination, \(R^{2}\), which has a value of 0.9232, indicates that 92.32% of the actual data indicates a good fit for the model. Moreover, the predicted and actual values are plotted in Figure 16, which shows an adequate linear relationship between the predicted and actual values, denoting that the regression model is adequate.