## 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  
To determine the effect of the initial void ratio on the matric suction, the test results of CCL and CL were compared. Both CCL and CL specimens are clay with no polyurethane and have the same initial characteristics, such as compaction water content, liquid limit, and grain size distribution. Figure 7 shows the WRC of CCL and CL, in which the logarithm of the matric suction was plotted against the moisture content. It can be observed in Figure 7 that the matric suction, regardless of the number of wet-dry cycles and initial void ratio, increases as the gravimetric water content decreases. Thus, the capability of the soil to hold water against gravity increases as the specimen moves to a drier state, which agrees with the usual behavior of soil as it dries. Similar behavior was observed by [PERSON] et al. [37], in which the relationship between the gravimetric water content and soil suction investigated in their study was unaffected by the initial conditions, such as the void ratio. It can be observed from Figure 7 that varying the initial void ratio did not have an effect at the higher suction range of around 30,000 to 200,000 kPa or 4.48 log kPa to 5.3 log kPa. The behavior of CCL and CL at the higher suction range agrees with the findings of [PERSON] et al. [38], [PERSON] et al. [37], and [PERSON] and [PERSON] [39]. According to their findings, the matric suction at a higher range is not influenced by the initial conditions such as compaction effort, initial void ratio, and compaction moisture content, because water films at these high suction ranges are widely influenced by osmotic and adsorptive  
Figure 7: Matric suction of compacted clay with varying initial void ratios. structure. Thus, it was inferred by previous studies that the soil structure, which is affected by said initial conditions, has a negligible influence on the soil-water behavior at a higher suction range. Data from previous studies agree with the data obtained that captured the negligible effect of the initial void ratio and the wet-dry cycle at the higher suction range. However, it can be observed in Figure 7 that there is a difference in the matric suction of CCL and CL at the lower suction range or below 30,000 kPa or 4.48 log kPa. CCL, which has a lower initial void ratio than CL, has a higher matric suction at the lower suction range. This indicates that varying the initial void ratio influences the matric suction at the lower suction range. As stated by [PERSON] et al. (2016), the compaction condition significantly affects the pore structure and, subsequently, the matric suction, since specimens with smaller pores, i.e., a smaller void ratio, desaturate slower. It can also be observed in Figure 7 that the number of wet-dry cycles affected the matric suction at the lower suction range. The area of the curve between the first and second wet-dry cycles is bigger compared to the area between the second and third wet-dry cycles for both CCL and CL specimens. Furthermore, increasing the number of wet-dry cycles from two to three did not affect the suction significantly, since it was already stable. The decrease in matric suction as the number of wet-dry cycles increased agrees with the findings of [PERSON] et al. (2018), in which the study inferred that the wet-dry cycle reduced the suction and water-holding capacity of the soil. Table 5 shows the three-way analysis of variance conducted, which inferred that varying the factors, such as moisture content and number of cycles, has a significant effect on the matric suction. There was no considerable cracking observed at the end of the first wet-dry cycle after the specimens were oven-dried, as shown in Figure 8. However, cracks immediately started to form during the first specimen re-saturation after oven drying. The deterioration of CCL and CL at crucial stages in the three wet-dry cycles are shown in Figures 9-12.