## 4 Geotechnical Characteristics of the PKS-Improved Fine Laterites
### Particle Size Distribution and Afterberg Limits
Moreover, BL31 + 00%PKS, BL31 + 15%PKS, BL32 + 00%PKS and B32 + 15%PKS can be  
Figure 12: UCBR versus MDD in the PKS-improved fine laterites. (**a**) BL31 sample; (**b**) BL32 sample; and SCBR versus MDD in the PKS-improved fine laterites. (**c**) BL31 sample; (**d**) BL32 sample. Figure 13: SCBR and UCBR in the PKS-improved fine laterites. used as base layers for roads with low pavement traffic (T1-T2). These are in accordance with S3, 75 MPa (BL31 + 00%PKS) and S4 bearing class and 150 MPa of elastic moduli [72]. The results of the unconfined compressive strength (UCS) and tensile strength (Rt) of BL31 improved specimens are presented in Table 6 and Figure 14.  
The UCS values increase progressively with the curing time and with increasing proportions of PKS. This means that the UCS varies from 1.07 MPa for natural mate \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**UCS (MPa)**} & \multicolumn{3}{c}{**Rt (MPa)**} \\ \cline{2-7}  & **Parameters** & **7 Days** & **14 Days** & **28 Days** & **7 Days** & **14 Days** & **28 Days** \\ \hline \multirow{4}{*}{100\%BL31 + 0\%PKS} & Min & 0.675 & 1.240 & 1.980 & 2.090 & 2.250 & 2.720 \\ \cline{2-7}  & Max & 1.182 & 1.560 & 2.510 & 2.250 & 2.600 & 3.070 \\ \cline{2-7}  & Mean & 1.070 & 1.541 & 2.122 & 2.241 & 2.521 & 3.001 \\ \cline{2-7}  & SD & 0.363 & 0.158 & 0.272 & 0.076 & 0.175 & 0.156 \\ \hline \multirow{4}{*}{85\%BL31 + 15\%PKS} & Min & 1.000 & 1.740 & 2.440 & 2.410 & 3.010 & 3.550 \\ \cline{2-7}  & Max & 1.110 & 1.820 & 2.590 & 2.500 & 3.210 & 3.700 \\ \cline{2-7}  & Mean & 1.071 & 1.792 & 2.531 & 2.462 & 3.174 & 3.653 \\ \cline{2-7}  & SD & 0.095 & 0.062 & 0.073 & 0.033 & 0.109 & 0.087 \\ \hline \multirow{4}{*}{75\%BL31 + 25\%PKS} & Min & 1.080 & 1.990 & 3.020 & 3.110 & 4.000 & 5.010 \\ \cline{2-7}  & Max & 1.743 & 2.830 & 3.310 & 3.410 & 4.310 & 6.130 \\ \cline{2-7}  & Mean & 1.403 & 2.600 & 3.160 & 3.204 & 4.080 & 5.800 \\ \cline{2-7}  & SD & 0.342 & 0.192 & 0.318 & 0.460 & 0.383 & 0.783 \\ \hline \multirow{4}{*}{65\%BL31 + 35\%PKS} & Min & 1.890 & 2.450 & 5.090 & 3.970 & 5.750 & 7.010 \\ \cline{2-7}  & Max & 1.890 & 2.830 & 5.713 & 4.890 & 6.510 & 8.560 \\ \cline{2-7}  & Mean & 1.890 & 2.600 & 5.630 & 4.420 & 6.060 & 7.983 \\ \cline{2-7}  & SD & 0.000 & 0.191 & 0.328 & 0.460 & 0.318 & 0.878 \\ \hline \multirow{4}{*}{55\%BL31 + 45\%PKS} & Min & 3.160 & 3.936 & 6.891 & 4.230 & 6.043 & 8.980 \\ \cline{2-7}  & Max & 3.160 & 4.950 & 7.912 & 5.020 & 7.960 & 9.931 \\ \cline{2-7}  & Mean & 3.160 & 4.710 & 7.670 & 4.901 & 6.962 & 9.711 \\ \cline{2-7}  & SD & 0.000 & 0.729 & 0.512 & 0.425 & 0.969 & 0.492 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Evolution of unconfined compressive strength (UCS) and tensile strength (Rt) of the BL31 material and its various mixtures with PKS. Max, Maximum; Min, Minimum; SD, Standard Deviation. Figure 14: Strength characteristics of the PKS-improved fine laterites. (**a**) UCS; (**b**) Rt. rial at 7 days of curing to 7.67 MPa for the stabilized material 65%BL31 + 45%PKS after 28 days [31; 91; 94]. A similar trend is observed for the Rt values. However, Rt is more sensitive than UCS. In fact, a natural material displays an Rt value of 2.24 MPa after 7 days of curing, while a value of 9.71 MPa is recorded for the optimal mixture (65%BL31 + 45%PKS) after 28 days. According to [44], the increasing values of UCS and Rt with the addition of PKS suggests a good adhesion between the soil and PKS. Consequently, the studied materials can be utilized for sub-base courses [16; 79].