# Improving Geotechnical Properties of Expansive Subgrade Using Sugar Cane Molasses and Cement
## 4 Results and Discussion
### Effect of Stabilizers on Arterberg Limits  
Consistency limits for soils treated with molasses and cement combination for 7 day curing periods are determined according to ASTM D-4318 [16] and presented in Table 5. \begin{table}
\begin{tabular}{c c} \hline
**Percent of Stabilizer** & **pH Value** \\ \hline Native & 8.20 \\ S\({}_{4,4}\) & 7.84 \\ S\({}_{4,8}\) & 8.07 \\ S\({}_{4,12}\) & 9.11 \\ S\({}_{8,4}\) & 13.19 \\ S\({}_{8,8}\) & 13.63 \\ S\({}_{8,12}\) & 13.74 \\ S\({}_{12,4}\) & 13.75 \\ S\({}_{12,8}\) & 13.18 \\ S\({}_{12,12}\) & 13.48 \\ \hline \end{tabular}
\end{table} 
Table 4: pH values after one-hour mix of soil and stabilizers. \begin{table}
\begin{tabular}{c c c c} \hline
**Mix Types** & **Soil** & **Molasses** & ** cement** \\ \hline S\({}_{12,4}\) & 84\% & 12\% & 4\% \\ S\({}_{12,8}\) & 80\% & 12\% & 8\% \\ S\({}_{12,12}\) & 76\% & 12\% & 12\% \\ \hline \end{tabular}
\end{table} 
Table 3: _Cont._In Table 5, Atterberg limit values for treated soils are presented. These values (liquid limit, plastic limit, and plasticity index) are crucial for understanding the soil's consistency and moisture response. The liquid limit (LL) and plastic limit (PL) generally decrease with the addition of molasses and cement, reflecting a reduction in the soil's ability to retain water. This leads to decreased plasticity, which is beneficial for stabilizing expansive soils. Furthermore, the optimum moisture content (OMC) decreases as the soil becomes more compactable with the addition of stabilizers, while the maximum dry density (MDD) increases, indicating improved compaction. The moisture content plays a critical role in this process, as lower OMC means the soil achieves maximum compaction with less water, enhancing its strength and reducing swelling potential. Therefore, the reduction in Arterberg limits corresponds to a decrease in OMC, allowing for better compaction and increased stability of the treated soil. Figure 5 shows the effect of molasses; the initial reduction in the liquid limit (LL) observed up to the S4,12 treatments can be attributed to the cation exchange and adhesive properties of molasses. However, when the molasses content increases to 8% and 12%, the LL also rises. This increase occurs because the higher concentration of molasses in clay soil leads to a reduction in the size of individual soil aggregates. The values of the plastic limit (PL) slightly decline with the addition of sugar cane molasses in addition to cement up to 12%, as shown in Figure 6. Eventually, this causes the soil to revert to a finer state, which enhances its water-holding capacity and results in an increased LL and plasticity index (PI). The PI values for soils treated with molasses range from 9.7% to approximately 12.9%, aligning with the findings of [PERSON] [21]. Regarding cement, the initial reduction in the soil's water-holding capacity and LL is due to the cation exchange process between the soil's cations and those in the cement. This exchange suppresses the thickness of the double layer by increasing the cation concentration, as noted by [PERSON] et al. [22]. Conversely, the decrease in LL with 8% cement can be attributed to a reduced pozzolanic reaction, which occurs due to the high concentration of Ca(OH)\({}_{2}\) when the cement content exceeds 4%. This pozzolanic reaction decreases the soil's water-holding capacity, thereby lowering both the LL and PL, as discussed by [PERSON] [23]. The combined effects of molasses and cement on the Atterberg limits suggest a significant reduction in the soil's water-holding capacity, which may result from interactions among molasses, cement, clay, and water. As previously mentioned, the cation exchange and adhesive properties of molasses contribute to this reduction, while the hydration and pozzolanic reactions of cement have a similar effect in soil-cement mixtures, as supported by [PERSON] et al. [24]. The high viscosity of molasses likely plays a crucial role in improving soil stability, similar to the effects of high-viscosity polymers in geosynthetic applications.