# Preparation, Characterization and Modeling of Unbound Granular Materials for Road Foundations
## 3 Results and Discussion
### The Afterberg Limits  
The Afterberg Limits are used primarily in classifying cohesive soil materials for engineering purposes. As the water content is increased, the consistency of a fine-grained soil changes from a semi-solid state to a plastic state and finally to a liquid state. The plastic limit (PL) is the point at which the consistency, caused by the soil water content, is transformed from a semi-solid state to a plastic state. The liquid limit (LL) is the point at which the consistency is transformed from a plastic state to a liquid state. In these studies, the Casagrande Liquid Limit Device was used for determining the liquid limit of the sample soils, according to UNE-EN 103103 [13]. The plastic limit was measured by the moisture content (%) at which the soil, when rolled into threads of 3 mm in diameter, will crumble. The results from the Afterberg Limits test are shown in Table 4.  
Soil stabilization by lime or hydraulic binder immediately produce a variation of the water content and modification of the geotechnical characteristics of the fine fraction, as due to the flocculation of the clayey fraction of the soil [14,15]. Figure 2 displays the plasticity index for different filler proportions in the stabilized soils prepared in this study. With the addition of lime, the plasticity of both tolerable and marginal soil was reduced, as previously reported by [PERSON] [16]. The addition of cement and microcement produced similar effects in the marginal soils tested: the plasticity index was reduced. However, both hydraulic binders caused an appreciable decrease in plasticity index (from 32% to 14% at the addition of 3% stabilizer in tolerable soil) followed by gradual increase with further additions (6% and 9%).  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Base Material** & **Filler** & **LL (\%)** & **PL (\%)** & **PI** \\ \hline Z25 & - & Non-plastic & & \\ Selected & - & Non-plastic & & \\ Suitable & - & 20.5 & 14.3 & 60.2 \\ Tolerable & - & 64.4 & 32.6 & 31.8 \\ Marginal & - & 134.0 & 62.5 & 71.45 \\ \hline \multirow{7}{*}{**Tolerable**} & 3\% Lime & 37.3 & 20.3 & 17.0 \\  & 6\% Lime & 38.6 & 26.2 & 12.4 \\  & 9\% Lime & 27.7 & 17.0 & 10.7 \\  & 3\% Portland CEMII/B-L & 35.5 & 21.9 & 13.6 \\  & 6\% Portland CEMII/B-L & 35.0 & 20.7 & 14.3 \\  & 9\% Portland CEMII/B-L & 34.7 & 19.9 & 14.8 \\  & 3\% Spinor A-12 & 34.0 & 19.8 & 14.2 \\  & 6\% Spinor A-12 & 34.5 & 20.2 & 14.3 \\  & 9\% Spinor A-12 & 37.0 & 21.8 & 15.2 \\ \hline \multirow{7}{*}{**Marginal**} & 3\% Lime & 124.5 & 62.8 & 61.7 \\  & 6\% Lime & 93.2 & 62.3 & 30.8 \\  & 9\% Lime & 90.0 & 68.3 & 21.7 \\  & 12\% Portland CEMII/B-L & 90.7 & 68.7 & 22.0 \\  & 15\% Portland CEMII/B-L & 88.0 & 67.5 & 20.5 \\  & 18\% Portland CEMII/B-L & 85.0 & 66.1 & 18.9 \\  & 12\% Spinor A-12 & 82.7 & 59.6 & 23.1 \\  & 15\% Spinor A-12 & 80.2 & 61.8 & 18.4 \\  & 18\% Spinor A-12 & 77.0 & 64.4 & 12.6 \\ \multirow{2}{*}{**NGA**} & 3\% Lime & Non-plastic & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Afterberg limits of classified and stabilized subbase materials used in this study. LL: Liquid Limit, PL: Plastic limit, PI: Plasticity index.