# Stabilization of Road Embarkments on Peat Soils Using Oil Shale Ash and Pozzolanic Additives
## Results and Discussion  
### Initial Lab Tests  
The results of stress-strain tests are shown in Table 7 and Figure 7.  
The results of the phase composition analysis for crystalline and semi-amorphous phases determined by the X-ray diffraction (XRD) method are presented in Table 8.  
The elemental compositions of samples T10, T11, and T17 determined by X-ray fluorescence spectroscopy (XRF) (spectrometer ZSX 400, Rigaku, Tokyo, Japan) are given in Table 9.  
The results of compression-deformation tests show that naturally occurring fibers in peat perform mechanically similarly to steel reinforcement or glass fiber admixtures in conventional cement-based concrete, with a difference appearing when compression occurs. The reinforcement effect and plasticity provided by the peat fiber to the composite are better, and the mechanical pressure exerted on the peat-ash composite is higher. Figure 8 shows that the compressive strength of the composite increases again under load after crossing the \"plateau\", unlike normal concrete. This may be due to the effect of heat from mechanical stress on the lignin contained in the naturally occurring fibers in the peat,  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \begin{tabular}{c} **Specimen** \\ **Maximum Force, mm** \\ \end{tabular} & \
\begin{tabular}{c} **Compressibility at** \\ **Force, kN** \\ \end{tabular} &
\begin{tabular}{c} **Maximum** \\ **Force, s** \\ \end{tabular} \\ \hline
1 & T-6 & 16.08 & 7.53 & 482.54 \\
2 & T-10 & 16.04 & 12.01 & 481.26 \\
3 & T-11 & 16.02 & 7.38 & 480.56 \\
4 & T-12 & 16.07 & 7.42 & 482.18 \\
5 & T-13 & 16.34 & 3.19 & 490.26 \\
6 & T-14 & 16.02 & 8.35 & 480.51 \\
7 & T-15 & 16.01 & 4.9 & 480.44 \\
8 & T-16 & 16.13 & 20.01 & 483.81 \\
9 & T-17 & 16.01 & 1.25 & 480.26 \\
10 & T-18 & 16.03 & 3.74 & 480.76 \\
11 & T-19 & 17.78 & 2.33 & 533.52 \\
12 & T-20 & 16.47 & 0.53 & 494.22 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Parameters and results of compression–strain tests.  
Figure 7: Compression–strain curves of test specimens listed in Table 7.  
As shown in Table 8, the content of the semi-amorphous CSH phase (hydrated semi-amorphous calcium silicate) increased almost four-fold in the order of T17 > T11 > T10, while the content of non-hydrated quartz showed the opposite trend. The quartz content decreased in the order of T10 > T11 > T17 from 33.6% in T10 to 10.3% in T11 and 6.8% in T17. The high SiO\({}_{2}\) content of specimen T10 also indicates that SiO\({}_{2}\) was added in excess, and its hydration and the rate of CSH gel (amorphous and semi-amorphous calcium silicate) formation were limited by the Ca\({}^{2+}\) ion content, resulting in lower plasticity of the specimen compared to other specimens. For specimens T10 and T11, which had a lower content of CSH gel (amorphous and semi-amorphous calcium silicate), the crystallization of alkaline feldspars proceeded faster, while for specimen T17, it proceeded significantly slower. The crystallization of alkaline feldspars was also described in our previous work [3].  
Among all samples, a relatively similar amount of the fully amorphous phase, which includes both the organic matter and a portion of the CSH gel, was present. Belite was detected only in specimen T17. The crystal phases of specimen T11 containing CFB ash also showed higher amounts of Mg- and Fe-bearing minerals.