## 4 Discussion  
After lime stabilization, the slurry with high water content revealed remolded yield stress, with significantly reduced soil compressibility prior to yielding. It has been shown that the remolded yield stress of soils is closely related to their structural properties [28]. In this study, the mixing of lime and slurry induced the flocculation of fine particles into flocs through ion exchange, forming a relatively stable soil structure. Meanwhile, the volcanic ash reaction produced various cementing substances, such as calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH), which further bound the flocculated structure. Under the combined action of ion exchange and volcanic ash reaction, the compressibility of the stabilized slurry was shown to substantially decrease. When the vertical effective stress exceeded the remolded yield stress, the structure of the stabilized slurry was destroyed, and its compressibility was close to that of the remolded slurry with a sharp rise in compressibility, which was consistent with a previous study [24].  
Due to the large specific surface area of clay, ion exchange reactions occurred easily, resulting in a greater stabilizing effect on the slurry with high clay content with a 1% lime dosage [29]. Meanwhile, clay proved more sensitive to the lime dosage than silt. When the optimal lime dosage was exceeded, the lime that did not participate in the reaction instead reduced the bonding force between soil particles, thus leaving little difference between the respective remolded yield stress values of the slurry with high clay content with 2% and 3% lime dosages [30].  
Figure 10: Microstructure of the four types of stabilized slurry with a 1% lime dosage. (**a**) Wenzhou soil sample, (**b**) Hangzhou soil sample, (**c**) Taizhou soil sample, (**d**) Zhoushan soil sample.  
Lime was also found to enhance the permeability of the slurry with high water content, due primarily to the increase in pore volume and diameter. After lime stabilization, the percentage of mesopores was observed to have risen while the percentages of micropores, pinholes, and macropores had all reduced. [PERSON] et al. [31] proposed that the percentage of mesopores should be regarded as the key factor in determining the permeability of the lime-stabilized slurry, and that although its variation trend is consistent with that of the permeability coefficient of specimens, micropores and pinholes have virtually no effect on the soil sample permeability due to the small pore throat size. In the existing studies, it was usually assumed that the reduction in mesopores and macropores in lime-stabilized soils was associated with a volcanic ash reaction, while the drop in micropores and pinholes was related to both ion exchange and a volcanic ash reaction [32; 33]. Further studies have established that the combined effects of ion exchange and volcanic ash reactions flocculate soil particles to form aggregates, resulting in reduced percentages of micropores and pinholes. Conversely, the cementation products generated by the volcanic ash reaction fill the pores, leading to smaller pore diameters. The above two reactions have furthermore been shown to take place simultaneously, and their primary and secondary effects should be deemed to relate to the lime dosage.  
The recommended lime dosages for actual engineering projects have been set to (i) 2% for slurry with high clay content in order to reduce its compressibility or enhance its permeability and (ii) 3% for slurry with high silt content.