## 4 Results
### Gravel Treated with Ash and Lime
#### 4.2.4 Dynamic Test  
To carry out the dynamic study of these mixes of gravels with ash and lime, first a reference static flexion test was conducted and then the dynamic loading test was performed.  
It should be mentioned that for the analysis of the behavior under dynamic loading, the mixes of gravel with ash and lime used were G-150, G-152 and G-153 due to the results obtained in the study of the simple compression strength at 28 days. The results of the static flexion test are shown in Table 9.  
The gravels with added ash only do not acquire any strength at 90 days. In the case of mixes with added ash and lime, it was observed that at 28 days of curing, the flexion strengths were too low. Moreover, these samples were prepared for the dynamic test with a pre-fissure, but as they were incapable of resisting this process, the samples with 28 days' curing were rejected and only the 90-day cured samples were selected. In the samples with more than 15% added ash, a clear decrease in densities can be seen, which affects the flexion strengths, reducing them and making them null, which did not occur in the simple compression test. Another clear symptom is that these samples are not sufficiently strong to resist the process of pre-fissuring, even after 90 days of curing (Table 9).  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**UCS (MPa)**} \\ \hline  & \multicolumn{3}{c}{**0\% Lime**} & \multicolumn{3}{c}{**2\% Lime**} & \multicolumn{3}{c}{**3\% Lime**} \\ \hline
**Days** & **7** & **28** & **90** & **7** & **28** & **90** & **7** & **28** & **90** \\ \hline Gravel & 0.161 & - & - & 0.359 & 0.485 & 0.586 & 0.24 & 0.392 & 0.528 \\ G-10\% & 0.353 & 0.666 & 0.822 & 0.478 & 0.628 & 2.375 & 0.635 & 0.805 & 2.454 \\ G-15\% & 0.456 & 0.653 & 0.561 & 0.567 & 1.091 & 2.753 & 0.623 & 1.301 & 2.680 \\ G-20\% & 0.461 & 0.471 & 0.557 & 0.639 & 0.929 & 3.053 & 0.603 & 1.188 & 3.212 \\ G-25\% & - & - & - & - & - & 2.932 & - & - & - \\ G-30\% & - & - & - & - & - & 2.633 & - & - & - \\ \hline \hline \end{tabular}
\end{table}
Table 7: Gravel Treated with Ash and Lime UCS (MPa).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Young’s Module (MPa)**} \\ \hline  & \multicolumn{3}{c}{**2\% Lime**} & \multicolumn{3}{c}{**3\% Lime**} \\ \hline
**Days** & **7** & **28** & **90** & **7** & **28** & **90** \\ \hline G-10\% & 28 & 40 & 117 & 25 & 37 & 100 \\ G-15\% & 26 & 46 & 123 & 26 & 48 & 120 \\ G-20\% & 31 & 48 & 142 & 26 & 52 & 150 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Young’s Module (MPa).  
After the static flexion test, the dynamic loading tests were carried out, starting with the gravel-ash-time in order to compare results with the gravel-cement. The first dynamic test was with G-152, varying the load applied starting from a value a little less than the one used in the static flexion test (2 KN): It withstood 3000 cycles, which is a very low value indicating that the material does not resist sufficiently (Figure 7a,b).  
The results show an excessively rapid growth of the crack, the deformations doubling in only 2400 cycles, even with relatively low loads. To analyze the behavior of the material under dynamic loading, very low loads must be used which do not correspond to those applied by traffic. Therefore, it can be concluded that the gravel-ash-time mix does not have good behavior under the dynamic loads generated by traffic. This means that this material must not be used or must be used in lower layers where the traction forces are small.  
The load corresponding to the flexion load was applied to the gravel-cement, leading to an excessive number of cycles for analysis; therefore, the load was increased up to 11.5 KN, producing breakage of the sample after 40,000 cycles.