# Expansive Soil Stabilization with Time, Cement, and Silica Fume
## 3 Testing Program  
The work is divided into two parts as follows, and the testing program is shown in Figure 2.  
The first group consisted of 10 tests and was used to investigate the free swell and swell pressure by using an oedometer test, as shown in Figure 3. The oedometer mold was prepared with the soil remolded at a unit weight of 17.5 kN/m\({}^{3}\) and water content of 16.5%, and then the mixing soil was stabilized with 5, 7 and 9% of lime, cement or silica fume. The percentages cement, lime and silica fume were recommended by many researchers [21; 22; 23].  
\begin{table}
\begin{tabular}{c c} \hline
**Index Property** & **Value** \\ \hline SiO\({}_{2}\) (\%) & 98.88 \\ \hline Al\({}_{2}\)O\({}_{3}\) (\%) & 0.01 \\ \hline Fe\({}_{2}\)O\({}_{3}\) (\%) & 0.02 \\ \hline CaO (\%) & 0.25 \\ \hline MgO(\%) & 0.01 \\ \hline K\({}_{2}\)O (\%) & 0.07 \\ \hline Na\({}_{2}\)O (\%) & 0.001 \\ \hline Others (\%) & 0.759 \\ \hline \end{tabular}
\end{table}
Table 4: Silica fume properties.  
\begin{table}
\begin{tabular}{c c} \hline
**Index Property** & **Value** \\ \hline Strength after 7 days (MN/m\({}^{2}\)) & 16 \\ \hline Strength after 28 days (MN/m\({}^{2}\)) & 28 \\ \hline Initial setting (min.) & 92 \\ \hline Final setting (min.) & 4.27 \\ \hline SiO\({}_{2}\) (\%) & 19.78 \\ \hline CaO (\%) & 63.7 \\ \hline MgO (\%) & 3.18 \\ \hline SO\({}_{3}\) (\%) & 2.16 \\ \hline C\({}_{3}\)A (\%) & 3.26 \\ \hline LOI (\%) & 0.88 \\ \hline \end{tabular}
\end{table}
Table 3: Cement properties.  
Figure 3: Consolidation test.  
Figure 2: Testing program.  
The other group consisted of 10 models and adopted the grouting process in the laboratory as a simulation of the field. The soil was prepared and mixed with bentonite and filled in a steel container of 400 \(\times\) 400 \(\times\) 400 mm dimensions. A footing of dimensions 60 \(\times\) 60 \(\times\) 10 mm was used to load the soil to investigate the load-carrying capacity of the soil and grouting soil with additives. A grouting probe of 10 mm in diameter and 120 mm in height was used to grout the liquid additives to the mixing soil. The grouting assembly is shown in Figure 4, and the grouting probe is shown in Figure 5. The mixing proportions are shown in Table 5. Each model was prepared as follows:  
1. The soil was divided into five parts in the steel container. The required percentage of lime, cement or silica fume was weighed and then mixed with water at a ratio of 1:2, as recommended by [PERSON] et al. [24] (i.e., for 5% of the additive, we need around 1000 gm of the additive material weight and around 2000 mL of water; for 7% of additive, 1400 gm of additive material is required and 2800 mL of water, while, for 9% of additive, 1800 gm of additive material is mixed with 3600 mL of water).
2. The slurry of additive material was poured into the slurry tank, which was closed completely.
3. The compressor in the control panel was opened to control the pressure in the slurry tank, and the gauge reading was monitored to be between 0.15 and 0.25 bar.
4. The grouting then started from the middle of the model to its edges to achieve the uniform distribution of the grouting slurry for all grouting holes.  
Figure 4: _Cont._  
Figure 4: Grouting assembly.