# Diatomaceous Soils and Advances in Geotechnical Engineering--Part I
## 3 Review of Progress in Geotechnical Lines
### Artificial Soils and Control of Variables in Diatomaceous Soils  
Kaolin is a clay in which the mineral known as kaolinite predominates; it is white, inert to chemical agents, odorless, electrically insulating, moldable, easy to extrude, resistant to high temperatures, non-toxic, and non-abrasive. Kaolinite comes mainly from the feldspars and micas of granitic rocks, developing in regions where precipitation is high and there is adequate drainage to ensure the washing of cations. Kaolinite is one of the most common clay minerals found in sedimentary and residual soils [90]. The plasticity and mechanical strength of kaolin are associated with the degree of packing of its particles and will be greater the finer its particle size distribution is. These properties are usually related to the content of the fraction smaller than 2 um[91]. Kaolinite has a lower plasticity than other clay minerals such as illite. In contrast to montmorillonite and upon wetting, the bonds between kaolinite particles are strong. It is not susceptible to expansion and has a comparatively low deformability and high shear strength. The reasons why kaolin is more stable in terms of its chemical behavior is because it has a \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Origin** & **Sample Details** & **LL** & **PL** & **PI** & **Source** \\ \hline \multirow{4}{*}{USA} & \multirow{4}{*}{Multispecies} & Casagrande & Rolls Method & \multirow{4}{*}{[5,10]} \\  & & 114–142 & 59–98 & & [5,10] \\  & & Cone 83–170 & Cone 65–124 & & \\ \multirow{4}{*}{Thailand} & Monospecies & 56 & 50 & 6 & [88] \\  & Sample depth & 109–120 & 88–93 & 21–88 & [89] \\ \multirow{4}{*}{Armenia} & \multirow{4}{*}{Sample depth} & \multirow{4}{*}{120–134} & \multirow{4}{*}{89–95} & \multirow{4}{*}{32–39} \\  & & 76 m & & & \\ \multirow{4}{*}{Japan} & \multirow{4}{*}{—} & 55–180 & & 28–115 & [87] \\  & & & & & \\ \multirow{4}{*}{Japan} & \multirow{4}{*}{Centric species–Sample depth} & \multirow{4}{*}{117} & \multirow{4}{*}{42} & \multirow{4}{*}{75} & [8] \\  & & 383 m—19\% clay content & & & \\ \multirow{4}{*}{Not defined} & Diatomaceous little & 172 & 94 & 78 & [67] \\  & & Monospecies & 140 & 121 & 19 & [85] \\ \multirow{4}{*}{Colombia (Siaachoque)} & Monospecies & 118 & 76 & 42 & [85] \\ \multirow{4}{*}{Colombia (Chivata)} & Monospecies & 132 & 87 & 45 & [85] \\  & & Monospecies & 120 & 94 & 26 & [29] \\ \multirow{4}{*}{USA, Florida} & \multirow{4}{*}{Soft rock (diatoms, clay, volcanic & 172.7 & 94.7 & 78 & [86] \\  & & ash) & & & \\ \multirow{4}{*}{China (Changbai)} & \multirow{4}{*}{–} & \multirow{4}{*}{175} & \multirow{4}{*}{153} & \multirow{4}{*}{22} & [14] \\  & & Sample depth 8–33 m & & & \\ \multirow{4}{*}{USA (Oregon Chiloquin)} & \multirow{4}{*}{Sample depth 8–46 m} & \multirow{4}{*}{73–100} & \multirow{4}{*}{35-37} & [15] \\  & & 97\%–71\% & & & \\ \multirow{4}{*}{USA (Oregon La Pine)} & \multirow{4}{*}{Sample depth 37–46 m diatom} & \multirow{4}{*}{75–95} & \multirow{4}{*}{50–55} & \multirow{4}{*}{22–45} & [15] \\  & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Consistency limits and plasticity index in DSs according to origin and type. low specific surface area and its cation exchange capacity (CEC) is lower than that of other minerals [90]. Mineralogical studies indicate that kaolin-type soils do not present expansion, since their components present low Atterberg limits and low plasticity compared to other types of clays due to their high contents of quartz [28]. Some characterization results obtained on kaolin samples are Gs: 2.68; LL: 62.4%; PL: 28.7%; and PI: 33.7% [28]. Comparatively, Ref. [92] reports Gs: 2.65; LL: 28.2%; PL: 16.5%; and PI: 11.7%. Kaolin is a type of clay usually used for the elaboration of artificial soil samples [14], with researchers often dosing it gravimetrically or volumetrically together with other components or independently in order to assess aspects such as its mineralogy, porosimetry, and microstructure [28].