## 4 Results and Discussion
### Effect of CAWA on the Geotechnical Properties  
#### 4.2.1 Modified Proctor Compaction Test Results  
The maximum dry density (MDD) values of the CACW-soil mixes with the addition of 2% cement were in the range of 2.123-2.256 g/cm\({}^{3}\), as shown in Figure 4. Considering the effect of CACW on the maximum dry density, it was observed that the effect of CACW on the maximum dry density was significant. The maximum dry density increased from 2.123 for plain soil to 2.174 and 2.256 g/cm\({}^{3}\) for the 5 and 10% addition of CACW, respectively. Thereafter, the maximum dry density decreased to 2.231 and 2.211 g/cm\({}^{3}\) with the further addition of 15% and 20% of CACW, respectively. This means that the addition of 10% of CACW filled the soil voids and enabled the production of extra-dense samples with robust strength characteristics, while at 10 and 20% of CACW, a decrease in the maximum dry density of the mix was detected (Figure 4).  
Figure 3: Chart of grain size distribution of soil and CACW.  
The high concentration of CACW, which was more than that required to fill the pore space in the soil-CACW mixture, may be responsible for the reduction obtained with 15 and 20% CACW. The density of samples did not improve as the WMD proportion rose above 10%. Instead, a decrease in the sample density was found.  
The influence of CACW content with 2% cement addition on the optimal moisture content (OMC) and the maximum dry density (MDD) is shown in Figure 5. The data in the figure clearly show that the increase in CACW percent was predominantly associated with an increase in the OMC. Due to the large surface area of CACW particles (i.e., high fineness) compared to soil; this behavior is expected, as it raises the water demand and, as a result, increases the optimal moisture content [40] (Figure 5).  
According to the dependencies shown in Figures 4 and 5, mathematical models for calculating and predicting the output parameters under consideration, which can be obtained in the course of regression analysis, are given as follows:  
Figure 4: The relationship between dry density and moisture content of soil\(-\)CAWA\(-\)2% cement mixes.  
Y denotes the maximum dry density and x denotes water content in Figure 4;  
\[\text{For soil alone y}=-0.0065\text{x}^{2}+0.0799\text{x}+1.8726\text{ R}^{2}=0.9924 \tag{1}\]  
\[\text{For soil}+5\%\text{ CACW}+2\%\text{ cement y}=-0.0081\text{x}^{2}+0.1093 \text{x}+1.8114\text{ R}^{2}=0.9924 \tag{2}\]  
\[\text{For soil}+10\%\text{ CACW}+2\%\text{ cement y}=-0.0072\text{x}^{2}+0.1116 \text{x}+1.8192\text{ R}^{2}=0.9399 \tag{3}\]  
\[\text{For soil}+15\%\text{ CACW}+2\%\text{ cement y}=-0.0075\text{x}^{2}+0.117 \text{x}+1.786\text{ R}^{2}=0.9417 \tag{4}\]  
\[\text{For soil}+20\%\text{ CACW}+2\%\text{ cement y}=-0.008\text{x}^{2}+0.1265 \text{x}+1.7339\text{ R}^{2}=0.9797 \tag{5}\]  
Similarly, y represents the maximum dry density, and x represents the CACW percentage in Figure 5:  
\[\text{y}=-0.0007\text{x}^{2}+0.0188\text{x}+2.1173\text{ R}^{2}=0.91 \tag{6}\]  
where y represents the optimum water content of the mix and x represents the CACW percentage in Figure 5 as well:  
\[\text{y}=0.1594\text{x}+7.3986\text{ R}^{2}=0.9865 \tag{7}\]