# CBR Predictive Models for Granular Bases Using Physical and Structural Properties
## 2 Materials and Methods
### Characteristics of Tested Materials
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{3}{*}{**Quarry**} & \multirow{3}{*}{**LL (\%)**} & \multirow{3}{*}{**PL (\%)**} & \multirow{3}{*}{**LVW (kg/m\({}^{3}\))**} & \multirow{3}{*}{**SD S**} & \multicolumn{3}{c}{**Directed Values**} & \multicolumn{3}{c}{**Corrected Values**} & \multirow{3}{*}{**Added**} & \multirow{3}{*}{**CE**} & \multirow{3}{*}{**CSR (\%)**} & \multirow{3}{*}{**USCS**} \\  & & & & \(\gamma\)4 (kg/m\({}^{3}\)) & & \(\gamma\)4 (kg/m\({}^{3}\)) & & & & & \\ \hline
1 & 27 & 12 & 1772 & 2.75 & 2240 & 8.0 & 2314 & 6.9 & 8.3 & 2692 & 111 & GW-GM \\  
Some samples were compacted according to the Modified Proctor compaction method and considering different water contents. Other samples were prepared using different compaction energies (CE) with the purpose of analyzing its effect on the CBR results. For such samples, the number of blows was modified. Thus, samples 1 to 4 from quarry 1, samples 8 to 11 from quarry 2, samples 18 to 21 from quarry 3, and samples 27 to 31 from quarry 4 were compacted according to the Modified Proctor compaction method, and the samples 5 to 7 from quarry 1, 12 to 17 from quarry 2, samples 22 to 26 from quarry 3, and samples 32 to 36 from quarry 4 were compacted with the same equipment and procedure but applying a different number of blows. The compaction energy and water content for each sample are summarized in Table 3.  
In addition to the main characteristics of the different samples, their volumetric and gravimetric parameters after compaction were obtained according to the procedures established by [21]. Such parameters are shown in Table 3 and include the volumetric weight (\(\gamma_{\rm m}\)), the volumetric weight of solids (\(\gamma_{\rm s}\)), the specific density of solids (\(\rm s_{s}\)), the relative density (\(\rm C_{r}\)), the void ratio (e), the porosity (n), the degree of saturation (\(\rm G_{w}\)), the degree of concentration of air (\(\rm G_{A}\)), the volumetric water content (\(\rm\theta\)), the degree of compaction with respect to dry volumetric weight from a compaction test (\(\rm G_{C}\)). The low CBR values of some samples from the same quarry were related to their low compaction energy. Therefore, CBR values were influenced by both the grain size distribution and compaction energy. Figure 1: Grain size distribution for the samples. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline \multirow{3}{*}{**Quantity**} & \multicolumn{3}{c}{**CE**} & \multicolumn{3}{c}{**Cray**} & \multicolumn{3}{c}{**Cray**} & \multicolumn{3}{c}{**Cray**} & \multicolumn{3}{c}{**Cray**} & \multicolumn{3}{c}{**Cray**} \\ \cline{3-14}  & **(Na-m(m)\({}^{n}\))** & **Sample** & \multicolumn{3}{c}{**Y4**} & **(Mg/m)** & **(\%)** & \multicolumn{3}{c}{**(Si)**} & \multicolumn{3}{c}{**(Si)**} & \multicolumn{3}{c}{**(Si)**} \\ \cline{4-14}  & & & & & & & & & & & & & & & & & & \\ \hline \multirow{11}{*}{1} & 2692 & 1 & 1772 & 1111 & 2753 & 2208 & 2291 & 2.75 & 8.3 & 93 & 0.25 & 20 & 92 & 7 & 184 & 95 \\  & 2676 & 2 & 1759 & 184 & 2757 & 2217 & 2237 & 2.76 & 4.9 & 83 & 0.24 & 20 & 55 & 44 & 109 & 97 \\  & 2609 & 3 & 1759 & 178 & 2757 & 2241 & 2394 & 2.76 & 6.8 & 91 & 0.23 & 19 & 81 & 18 & 152 & 98 \\  & 2673 & 4 & 1759 & 147 & 2757 & 2197 & 2496 & 2.7 & 9.8 & 20 & 20 & 74 & 25 & 152 & 108 \\  & 786 & 5 & 1616 & 98 & 28104 & 2041 & 2226 & 2.81 & 8.5 & 100 & 0.38 & 27 & 67 & 32 & 185 & 100 \\  & 601 & 6 & 1616 & 49 & 2815 & 1957 & 2991 & 2.81 & 6.8 & 80 & 0.44 & 30 & 43 & 56 & 134 & 96 \\  & 602 & 7 & 1616 & 28 & 2815 & 1986 & 1986 & 2.81 & 5.0 & 87 & 0.46 & 32 & 29 & 70 & 9.5 & 100 \\ \hline \multirow{11}{*}{2} & \multirow{3}{*}{2642} & 8 & 2158 & 72 & 2634 & 2158 & 2248 & 2.63 & 4.2 & 83 & 0.22 & 18 & 50 & 50 & 9.0 & 83 \\  & & 9 & 2230 & 86 & 2634 & 2230 & 2248 & 2.63 & 5.3 & 100 & 18 & 15 & 77 & 23 & 117 & 100 \\  & 10 & 2192 & 72 & 2634 & 2192 & 2333 & 2.63 & 6.4 & 91 & 0.20 & 17 & 84 & 16