Basics of Clay Minerals and Their Characteristic Properties

Abstract

Clay minerals such as kaolinite, smectite, chlorite, micas are main components of raw materials of clay and formed in presence of water. A large number of clays used to form the different structure which completely depends on their mining source. They are known as hydrous phyllosilicate having silica, alumina and water with variable amount of inorganic ions like Mg2+, Na+, Ca2+ which are found either in interlayer space or on the planetary surface. Clay minerals are described by presence of two-dimensional sheets, tetrahedral (SiO4) and octahedral (Al2O3). There are different clay minerals which are categorized based on presence of tetrahedral and octahedral layer in their structure like kaolinite (1:1 of tetrahedral and octahedral layers), smectite group of clay minerals (2:1 of tetrahedral and octahedral layers) and chlorite (2:1:1 of tetrahedral, octahedral and octahedral layers). The particle size of clay minerals is <2microns which can be present in form of plastic in presence of water and solidified when dried. The small size and their distinctive crystal structure make clay minerals very special with their unique properties including high cation exchange capacity, swelling behavior, specific surface area, adsorption capacity, etc. which are described in this chapter. Due to all these unique properties, clay minerals are gaining interest in different fields.

Nanotechnology Incorporation into Road Pavement Design based on Scientific Principles of Materials Chemistry and Engineering Physics

“…The engineering properties of the naturally available materials will change considerably over time, depending on the stage of chemical weathering (Figure 11 (recreated from [40])). As previously discussed, the mineral composition with specific reference to the silicon content, can have a considerable influence on the bond strengths achieved with the material when using a specific nano-modification of a stabilising agent.…”

“…The "clay problem" is a subject that in itself requires extensive discussion which will not be covered in any detail within this article. In order to appreciate the considerable challenges offered by materials containing a high percentage of clay, the properties of some of the most commonly found clays are summarized in Table 5 (based on [40]). 5 is of high importance when stabilising materials containing high percentages clay using a nano-silane modifications and the selection of an applicable stabilising agent.…”

Physicochemical Properties of Organophilic Clay Developed Using Hexadecyltrimethylammonium Chloride (HDTMAC) Modifier

“…This property of clay arose from isomorphous substitution, a crystal lattice defect in which a given ionic series may be replaced by another in a crystal lattice [24]. According to Neeraj and Chandra [4], values of CEC range from 3-15 in kaolinites through 15-40 in chlorites and illites, 70-100 in montmorillonite and 100-150 in vermiculite.…”

“…Iron substitute for aluminum and magnesium to varying degrees and appreciable quantity of potassium, sodium and calcium are frequently present [3]. Based on their structures and chemical compositions, the clay minerals can be divided into four main classes of kaolinite, smectites, illites and micas [4]. However, Sarkar et al [5] and Walter [6] refer to two or three classes of clays since illites are sometimes referred to as a 2:1 layer and not a 2:1:1.…”

Nanotechnology Incorporation into Road Pavement Design Based on Scientific Principles of Materials Chemistry and Engineering Physics Using New-Age (Nano) Modified Emulsion (NME) Stabilisation/Enhancement of Granular Materials

“…The "clay problem" is a subject that in itself requires extensive discussion, which will not be covered in any detail within this article. In order to appreciate the considerable challenges offered by materials containing a high percentage of clay, the properties of some of the most commonly found clays are summarized in Table 5 (based on [40]). The specific surface area of the different clays (in m 2 /g) shown in Table 5 is of high importance when stabilising materials containing high percentages of clay using a nanosilane modifications and the selection of an applicable stabilising agent.…”