# Evaluating Biosedimentation for Strength Improvement in Acidic Soil
## 4 Conclusions  
Substantial construction projects impact the economy, society and the environment over their life cycles [54], where weak soil stability plays a key role in construction sustainability. As marine clay is a weak soil, it is normally found in coastal regions around the world, such as; seas, lakes, ocean shores and riverbanks. It usually extends to enormous depths underneath the earth's surface. It is also notorious for being involved in landslides and large settlements. Special foundation systems, such as piles or soil replacements, are usually costly solutions compared with the proposed structure cost itself and require high quality control to meet their purpose: balance the essentials to be generated among the economic and environmental aspects [54; 55]. Conducting electrokinetic (EK) stabilization of soft acidic soil using the MICP phenomenon on a large-scale specimen is very important for improving soil environmentally. Nevertheless, no study has measured or assessed this previously mentioned experiment that encourages soil improvement adoption. This study aimed to cover this gap by highlighting the use of electrokinetic (EK) stabilization of soft acidic soil using the MICP for achieving soil project sustainability. The feasibility of large-scale marine clay soil treatment was examined, where the following conclusions were drawn:  
1. For the distance effect, as the distance increased by 150 mm between the two electrode cells, the shear strength decreased by 50%, where the maximum undrained shear strength was achieved by D45, which was 28.14 kPa, and 14.50 kPa was achieved for D60 at the anode cell. 2. Furthermore, the variation in shear strength after treatment along the soil specimen from the anode to the cathode was significant, where it decreased gradually until it reached the minimum values at the cathode. The minimum values were lowered by more than a half of the maximum values for both D45 and D60. 3. For the compressibility, both D45 and D60's compressibility indices were reduced significantly compared with natural soil (N), where for the fines activity, all Arterberg  
Figure 14: Erosion of the graphite bars (**a**) after treatment compared with (**b**) the initial condition. Figure 15: The negative electrode solution and the zone around the graphite bars are colored black after treatment. limits were also significantly enhanced, and the soil changed from OH to OL for D45 and D60. Therefore, the treated soil could sustain loads with lesser deformations compared with non-treated soils. 4. In addition, the pH value increased gradually and remained higher than 9.0, which guaranteed bacterial activity during the treatment process. This was due to the high rate of bacterial activity in the first 48 h in the production of NH\({}_{3}\). 5. After treatment for both the D45 and D60 specimens, the perforated walls were clogged at both the anode and cathode but were more significant for the anode. This was a result of the maximum accumulation of CaCO\({}_{3}\) precipitation at the anode side compared with the cathode side by at least 10 times. 6. For soil electric conductivity, it was observed that the soil resistance increased gradually until the end of the treatment from 25-30 V to 55-60 V. This reflected the increase in soil density, as the electrical potential deference increased significantly after treatment. 7. XRF detected that the precipitation of calcium carbonate (CaCO\({}_{3}\)) was achieved for both D45 and D60, with higher precipitation for D45. However, XRD detected that the soil mineralogy remained the same after EK treatment with biomineralization. The precipitation was 1.18% of the specimen's total weight for D45 and 0.83% for D60. 8. SEM-EDX showed soil texture enhancement, and mapping images showed the coating of particles by calcium carbonate (CaCO\({}_{3}\)), which was the reason for void reduction and strength enhancement after treatment, and therefore the soil properties were enhanced in terms of compressibility.