# Static Properties of Kaolinite Samples from Different Structures and the Influence of Strain Rate
## 4 Determination of Strain Rate and Experimental Details
### Shear Strength Formula Considering the Influence of Strain Rate
#### 5.3.2 Analysis and Discussion  
The strain rate sensitivity parameters of the flocculated and dispersed samples prepared from the kaolin used in this study were 4.79% and 2.31%, respectively. The shear strength-strain-rate relationships of the two structures are shown in Figure 13. When the strain rate of the flocculated sample was 0.012%/min and that of the dispersed sample was 0.005%/min, the shear strengths of the dispersed and flocculated samples were very close. When the two-structure samples were subjected to a strain rate of 0.005%/min, the shear strength of the dispersed sample was 3.94% higher than that of the flocculated sample. When the two-structure samples were subjected to a strain rate of 0.012%/min, the shear strength of the dispersed sample was 1.74% higher than that of the flocculated sample. The use of different strain rates underestimated the difference in the shear strength between the two structural samples.  
[PERSON] et al. [19] conducted triaxial undrained shear tests on flocculated and dispersed samples at the strain rates of 0.07%/min and 0.05%/min, respectively. The results showed that under an effective confining pressure of 200 kPa, the shear strength of the dispersed sample was 25.81% higher than that of the flocculated sample. [PERSON] [18] calculated the strain rates for flocculated and dispersed samples as 0.05%/min and 0.008%/min, respectively, using Equations (1)-(3). At these strain rates, the shear strength of the flocculated sample and dispersed sample is 129.02 kPa and 190.85 kPa, respectively. The shear strength of the dispersed sample is 47.94% higher than that of the flocculated sample. The kaolin used by [PERSON] was commercial kaolin (SC-25) with a liquid-limit moisture content of 62%, plasticity index of 30%, and specific gravity of 2.63. Based on the consolidation curves, the \(C_{a}/C_{c}\) values for the flocculated and dispersed samples are 0.0260 and 0.0275, respectively, calculated by Equation (9), the strain rate sensitivity parameters for the flocculated and dispersed structure samples are calculated to be 6.17% and 6.54%, respectively. both fall within the range of 5.9% to 12.2% proposed by [PERSON] and [PERSON] [37]. The strain-rate sensitivity parameters of the dispersed and flocculated kaolin samples were similar. For SC-25 kaolin, an increase in the strain rate by a factor of 10 increased the undrained shear strength by approximately 6%. Based on these data and Equation (8), the plots of the shear strength and strain rate for the two SC-25 kaolin structures are shown in Figure 14. If the strain rates used in this study were 0.05%/min for the flocculated sample (point F) and 0.008%/min for the dispersed sample (point D), the shear strength of the dispersed sample would be 47.94% higher than that of the flocculated sample. If both structural samples were tested at a strain rate of 0.05%/min (points D\({}^{\prime}\) and F), the shear strength of the dispersed sample would be 56.22% higher than that of the flocculated sample. If both structure samples were tested at a strain rate of 0.008%/min (points D and F\({}^{\prime}\)), the shear strength of the dispersed sample would be 55.34% higher than that of the flocculated sample[PERSON]  
It is evident that using different strain rates for samples with different structures underestimates the difference in the shear strength between the two structures. To study the effect of the structure, it was necessary to eliminate the influence of the strain rate. Considering these results, this study suggests that the best approach for comparing clay samples with the same mineral composition but different structures is to use the same strain rate[PERSON]