# Compression Behavior of Rubber-Bentonite Mixture under Different Salinities
## 2 Results and Discussions
### Modulus of Compression Change of MX80 Bentonite/Rubber Mixture
#### 2.2.1 Effect of Rubber Content on Compression Modulus under Different Vertical Loads  
Figure 5 shows the variation in the compressive modulus under different vertical loads and rubber contents in a 0.1 mol/L NaCl solution environment. The graph indicates a consistent trend in compressive modulus, where it increases with increasing percentage of rubber particles, regardless of the magnitude of the vertical load. The compressive modulus  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Rubber Content**} & \multicolumn{2}{c}{**Solution Concentration/Vertical Load**} & \multirow{2}{*}{**100**} & \multirow{2}{*}{**200**} & \multirow{2}{*}{**300**} & \multirow{2}{*}{**400**} & \multirow{2}{*}{**Mean Value**} & \multirow{2}{*}{**Standard Deviation**} & \multirow{2}{*}{**Variance**} \\ \cline{3-3} \cline{6-9}  & 0 & & & & & & & \\ \hline \multirow{3}{*}{0} & 0 & 2.702703 & 1.550388 & 1.818182 & 2.222222 & 2.073 & 0.502 & 0.252 \\ \cline{  
reaches its maximum value when the rubber particle content reaches 20%. As the rubber particle content further increases, the compressive modulus starts to decrease. Additionally, the compressive modulus was influenced by different vertical loads. Specifically, at a vertical load of 100 kPa, the compressive modulus was higher but decreased with increasing vertical load. At a vertical load of 200 kPa, the compressive modulus was the lowest, and it gradually increased with the increasing vertical load, reaching its maximum value at a vertical load of 400 kPa. These observations emphasize the importance of considering load conditions when evaluating the behavior and performance of materials, highlighting the influence of vertical load on the compressive modulus. Figure 6 illustrates the variations in compression modulus regarding rubber content and different vertical loads for various salt solution concentrations. Figure 6a shows the environment without NaCl, Figure 6b shows the environment with 0.5 mol/L NaCl, and Figure 7c shows the environment with 1 mol/L NaCl. The graph reveals that the compression modulus increased within the vertical load range of 300 kPa to 400 kPa. Additionally, at a vertical load of 400 kPa, the compression modulus demonstrated an upward trend with increasing salt solution concentration. Moreover, for a rubber mass content of 40%, the sample's compression modulus under a vertical load of 200 kPa in the 0 mol/L NaCl solution surpassed that of other vertical load conditions. However, as the salt solution concentration rose, the compression modulus of the B6T4 sample at a vertical load of 200 kPa gradually declined. [PERSON] et al. [28] found that with an increase of solution concentration, the reduction rate of the compression index increased. In the high-concentration solution, the orientation of bentonite particles was more condensed to prevent settlement, and the compression index reduced. However, when the rubber fiber content reached 15%, the compression index of the sample increased slightly. Figure 5: The variation in compression modulus with rubber content and under different vertical loads in a 0.1 mol/L NaCl solution. These observations indicated that increasing the rubber content to 40% effectively strengthened the sample's compressive resistance in the absence of solute ions in salt solutions at this particular ratio. Nonetheless, as the salt solution concentration increased, solute ions permeated the internal structure of the sample, creating a disconnection between MX80 and MX80. The results of this study are consistent with the results of the previous studies of the literature. Figure 6: Relationship between rubber content and compression modulus under different vertical loads: 0 mol/LNaCl solution (**a**), 0.5 mol/LNaCl solution (**b**), and 1 mol/LNaCl solution (**c**). Figure 7: Relationship between vertical load and compression modulus for 0 mol/LNaCl solution (**a**) and 0.5 mol/LnaCl solution (**b**) for different samples. bentonite and rubber particles.