# Static Properties of Kaolinite Samples from Different Structures and the Influence of Strain Rate
## 3 Physical Properties and Microscopic Characteristics of Flocculated and Dispersed Samples  
To ensure the consistency and repeatability of all the samples, it was first necessary to ensure that the quality and proportion of each batch of slurry were consistent and that the mass of the slurry in each consolidation cylinder was fixed. Before each test, as shown in Figure 3, the water content of the samples was measured at nine points. The results of the water content tests are summarised in Table 1. The difference between the water content at the nine measurement points and the average water content did not exceed 1%, ensuring good uniformity of the samples. The water content of the flocculated structure samples was controlled and ranged from 45.5% and 46.5%, that of the dispersed structure samples was controlled and ranged from 39.7% and 40.7%, and the difference in the water content of the samples was controlled and attained values within 1% to ensure repeatability. Table 2 presents the physical properties of flocculated and dispersed kaolin. Compared with the flocculated samples, the dispersed samples have a higher density and lower water content. The liquid limit of dispersed samples is lower than that of flocculated samples; however, their plastic limits were almost the same, with the plasticity indices of the dispersed and flocculated samples being 15 and 37, respectively. In addition, the permeability coefficients in both directions of the flocculated samples were similar, whereas the permeability coefficients in both directions of the dispersed samples differed significantly, and the permeability coefficient of the dispersed sample in the vertical direction is the smallest (Figure 4). Figure 2: Consolidation process of flocculated and dispersed samples. SEM and MIP tests were conducted on flocculated and dispersed samples to study the structures of the two types of samples. Cut some soil samples with dimensions of 1 cm \(\times\) 1 cm \(\times\) 2 cm from the specimen, immediately place them into a liquid nitrogen tank until complete freezing had occurred, then introduce all the samples into the freeze-drying device. After the sublimation is complete, some samples are used for SEM tests with a magnification of 10,000 times while others are broken in half to form 1 mm\({}^{3}\) samples for MIP tests. Figure 5 shows the SEM images of the samples at a magnification of 10,000 along the vertical direction. This confirms that the prepared samples have different structures; the clay platelets in the flocculated structure exhibit a random orientation with edge-to-face \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Sample** & **Point 1** & **Point 2** & **Point 3** & **Point 4** & **Point 5** & **Point 6** & **Point 7** & **Point 8** & **Point 9** &
\begin{tabular}{c} **Average Water** \\ **Content (\%)** \\ \end{tabular} \\ \hline Flocculated & 45.3 & 45.9 & 46.1 & 46.1 & 45.9 & 45.4 & 45.7 & 45.5 & 45.8 & 45.7 \\ \hline Dispersed & 40.6 & 40.5 & 40.3 & 41.0 & 40.4 & 40.3 & 40.6 & 40.1 & 39.8 & 40.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Results of water content test of flocculated and dispersed samples. Figure 4: Permeability coefficient-void-ratio curves of kaolin clay for flocculated and dispersed samples in vertical and horizontal directions. Figure 3: Selected points for water content test. contacts (Figure 5a) and exhibit a layered arrangement with face-to-face contacts in the dispersed structure (Figure 5b). In Figure 6a, it is clear that the accumulated mercury volume for the flocculated sample is higher than that of the dispersed sample. Figure 6b shows that the flocculated sample contains much larger pores (>5 \(\upmu\)m) than those of the dispersed sample, which indicates that compared to the dispersed samples, the flocculated samples have a larger initial pore volume and larger-sized pores. Figure 5: Scanning electron microscopy images: **(a)** flocculated and **(b)** dispersed samples.