## 4 Results and Discussion
### Stabilized Dredged Material  
#### 4.3.1 Compaction Behavior  
[PERSON] and [PERSON] [25] added lime, FA, and PC to several soil types and showed that additives could have different effects when added to different soils. Further addition of these additives did not significantly increase the MC but did increase the dry density. This effect can be partly attributed to the higher density of FA compared to HL and partly due to the spherical shape of FA particles, which enhances packing through its rolling effect. The addition of HL and FA at an FA/HL ratio of 2.3 increased the OMC, and inclusion of 15% PC slightly increased the \(\gamma_{\text{d(max)}}\)[23]. The increase in \(\gamma_{\text{d(max)}}\) can be partly due to the round particles of FA which facilitate particle packing and thus compaction, and partly due to the higher specific gravity of FA and PC compared to untreated DM.  
All samples were tested for optimum moisture content (OMC) and maximum dry density \(\gamma_{\text{d(max)}}\) according to ASTM D698 [37] and using different amounts of FA, HL, and PC while keeping the FA/HL ratio at the optimum value of 2.3. To demonstrate the effect of stabilizers on the compaction characteristics of the stabilized dredged material (SDM), the moisture-density relations of the mixes were determined and are shown in Figures 4-6. In these figures, the legend follows Table 2 and indicates the relative amount of HL/FA/PC, respectively.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Tests Conducted** & **Property Description** & **Value** \\ \hline \hline \multirow{4}{*}{Particle Size} & \% Passing No. 200 & 86.9 \\  & \% Sand & 9.4 \\  & \% Gravel & 3.7 \\ Unconfined Compressive & & 283 (41 psi) \\ Strength (kPa) & & 15.9 \\ Dry Unit Weight (kN/m\({}^{3}\)) & & 68–82\% \\ Moisture Content (\%) & & 2.69 \\ Specific Gravity & & 12–18\% \\ Organic Content & & 101 \\ Proctor & \(\gamma_{\text{d,max}}\) (lb/ft\({}^{3}\)) & 101 \\  & \(\omega_{\text{opt}}\) (\%) & 21 \\  & Liquid Limit & 52 \\ Atterberg Limits (\%) & Plastic Limit & 24 \\  & Plasticity Index & 28 \\ Classification (USCS) & OH—Organic clay of medium to high plasticity organic silt \\ \hline \hline \end{tabular}
\end{table}
Table 3: Preliminary test results for DM.  
Figure 5 presents the compaction variations at a Portland cement (PC) content of 10%. Increasing the amount of fly ash and hydrated lime slightly increased the moisture content (MC) from a maximum of 23% to 28%. It has been previously reported that Portland cement can slightly decrease OMC and increase \(\gamma_{\text{d(max)}}\)[1]. [PERSON] et al. [32], studying the effects of HL and FA on the same type of DM, reported that HL increased the OMC while lowering the \(\gamma_{\text{d(max)}}\), whereas FA decreased the OMC but increased the \(\gamma_{\text{d(max)}}\). The same trend was observed with a PC content of 15% and varying contents of FA and HL as depicted in Figure 6. Figure 7 compares mixes containing HL/FA of 15/34.5--which resulted in the highest \(\gamma_{\text{d(max)}}\)--with varying PC contents (10, 15, and 20). It was observed that increasing the PC content from 10% to 20% slightly increased the \(\gamma_{\text{d(max)}}\). Samples containing FA at 57.5%, HL at 25%, and 15% PC exhibited almost the same OMC as those with 10% PC but had a slightly larger \(\gamma_{\text{d(max)}}\). This effect may be due to the higher specific gravity of PC (3.15) compared to DM (2.69), FA (2.7), and HL (2.3).  
Figure 5: Compaction data for varying contents of HL and FA (for PC = 10%).  
Figure 6: Compaction data for varying contents of HL and FA (for PC = 15%).