# Laboratory Testing and Analysis of Clay Soil Stabilization Using Waste Marble Powder
## 3 Results and Discussion
### The Mechanical Behavior of Stabilized and Unstabilized Soil  
3.3.1. The Impacts of Water Content on the UCS  
It is intriguing to observe that soil type, additive type, water content, and curing time all substantially determine the maximum UCS of treated and untreated soil samples. The UCS of unmodified and modified clay samples as a function of water content and curing time is shown in Figure 8. The results show that as the WMP increases, the UCS of X1, X2, X3, X4, and X5 increase and then decrease slightly at X6, while the maximum UCS was obtained at 28 days of curing and with the addition of X5 marble powder, with the UCS values at dry moisture content (DMC), optimum moisture content (OMC), and wet moisture content (WMC) paths of 472 kN/m\({}^{2}\), 661 kN/m\({}^{2}\), and 540 kN/m\({}^{2}\), respectively. Figure 7: The amended and unamended soil sample’s compaction characteristics. This study's systematic optimization of WMP dosage, moisture content, and curing time provides new insights into maximizing UCS. In particular, the peak UCS at optimal moisture content is consistent with compaction theory. [PERSON] et al. and [PERSON] et al. reported identical results [1] in contrast to [PERSON]'s and [PERSON]'s studies, which found that following a 7-day curing period of fine-grained soil stabilized with WMP, the increment in UCS is greater for samples compacted with DMC than those compacted with OMC and WMC [47], where the peak UCS occurred at lower moisture contents. Furthermore, in contrast, [PERSON] et al. [43] observed that the UCS of CH soil stabilized with bentonite and bagasse ash rises with increasing water content up to a certain point and that the strength is higher for WMC than for DMC and OMC. This demonstrates the distinct reactivity and stabilizing effect of the strengthening agent and the soil. In addition, this study established a novel correlation between UCS results and ultrasonic pulse velocity measurements to characterize strength enhancement comprehensively. Compared to previous research, the integrated experimental-modeling methodology that combines UCS, UPV, and ANN simulations provides a more comprehensive approach. The three compaction paths detailed the above pattern: Path I, or the dry path of optimum, has pores of a bigger size, some of which cannot be entirely filled and bonded with the admixture due to larger pores. Moreover, the amount of water consumed is enough for performing chemical reactions due to the fact that it contains low water content [51]. On the other hand, Path II, or the optimum path, shows that higher water content can help with strength development by allowing for more efficient reactions between the marble powder and clay particles. The cation exchange process also substantially alters soil texture and structure, which can ultimately impact the porosity and volume capacity of  
Figure 8: Depiction of the maximum UCS of amended and unamended clays influenced by water content and curing time. the soil particles [52]. Finally, Path III, or the wet path of optimum, involves increasing the moisture content beyond the OMC. This increase in moisture content leads to a decrease in electrolyte concentration, increasing the expansion of the dispersed twofold layer and the distance between clay particles and alumina-silicate unit layers. This reduction in internal friction and cohesiveness is due to water entry into the pores [43]. As more water is added, the continual capillary moisture reduces suction, which lessens strength when moisture exceeds an optimal value. The dispersed structure becomes more homogeneous when added water decreases the UCS [53]. The function of marble in modifying the Soil Water Retention Curve (SWRC) of the samples is to increase the soil's water-holding capacity. As a porous material, marble dust can absorb and retain water, increasing the available water content of the soil [54]. The addition of marble and the resulting increase in strength is not directly related to the change in soil stress.