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One-dimensional constitutive relations of soils
Published in Jian-Hua Yin, Guofu Zhu, Consolidation Analyses of Soils, 2020
Illite is one of three clay minerals. Montmorillonite is the most highly plastic and exhibits the largest creep under stress. Kaolinite has the lowest plasticity and the smallest creep among the three clay minerals. Illite is in the middle with moderate plasticity and creep. Yin (1990) did a multi-stage oedometer test, a stepped-changed CRSN test and a relaxation test. The oedometer test data was used to calibrate the 1-D EVP model with all parameters in Table 1.1. The calibrated model was used to predict the time-dependent behavior of the illite in the CRSN test and relaxation test. Figure 1.12 shows measured and predicted relationships of vertical effective stress σz'versus time t of illite from a relaxation test (Yin, 1990). It is seen that the vertical effective stress σz' decreases with time duration at a decreasing rate.
Minerals, rocks, discontinuities and rock mass
Published in Ömer Aydan, Rock Mechanics and Rock Engineering, 2019
The atomic structure of clay minerals is basically similar to micas, and they generally occur as minute, platy crystals. An important characteristic is their ability to lose or take up water according to temperature and the amount of water present in a system. Some clay minerals contain loosely bonded cations, which can be easily exchanged for others. Clay minerals are produced by the degradation of silicates or other silicate glasses. Kaolinite, illite, montmorillonite, vermiculite and palygorskite are well-known clay mineral groups. Kaolin is the main constituent of ceramics. Illite is a common clay mineral, and clay in soil mechanics is constituted by illite clay minerals. Montmorillonites (smectite group) are formed by the alteration of basic rocks or other silicates low in K under alkaline conditions. Na-type montmorillonite is especially notable for losing or taking up water and associated volumetric changes.
Rock Forming Minerals
Published in Aurèle Parriaux, Geology, 2018
Technically it forms aggregates with moderate plasticity that are not very susceptible to swelling by water absorption (Chap. 13). Illite is used in the terra cotta industry, primarily in the area of construction materials (bricks, tiles, etc.).
The tensile and swelling behavior of cement-stabilized marine clay reinforced with short waste fibers
Published in Marine Georesources & Geotechnology, 2019
Qiang Li, Jinhuang Chen, Huixiao Hu
The XRD experiments show that the crystals in the marine clay contain illite and oblique chlorite composition in addition to quartz, as shown in Figure 4(a). The crystal structure of illite is 2:1, and its molecular formula is K2(Al⋅Fe⋅Mg)4 (SiAl)8O20(OH)4⋅nH2O; the crystal structure of the oblique chlorite is 2:1:1, and its molecular formula is (Mg⋅Fe⋅Al)12(SiAl)8O20(OH)16. In both types of clay minerals, due to the adsorption of potassium ions between the crystal layers or the sandwich of a layer of magnesium hydroxide, a strong bonding effect is exerted on the adjacent two crystal layers, so the minerals themselves are less inflated. Both the clay minerals are typical layered structure silicate mineral. The structure of the marine clay is observed by SEM, as shown in Figure 4(b), the mineral aggregate is scaly, which is consistent with the mineral components.
Physico-chemical characteristics of some Lesotho’s clays and their assessment for suitability in ceramics production
Published in Particulate Science and Technology, 2018
Monaheng Masheane, Lebea Nthunya, Mukuna Mubiayi, Thimothy Thamae, Sabelo Mhlanga
Natural clay minerals include kaolinite, quartz, mica, hematite, chlorite and illite (Kirkpatrick 1983; White 1987; Murray 1999; Anthony et al. 2011; Pohl 2011; Aramide 2012). Quartz (the principal constituent of silica sand), quartzite and ganister occur as an impurity in most clays, whereas kaolinite is a typical clay mineral found in most brick-making raw materials. It exhibits good sintering behavior, has a high melting point and forms no glass phase when firing to the relatively low brick manufacturing temperatures (900°C) (White 1987; Pohl 2011). Mica is an important rock-forming mineral in igneous, metamorphic and sedimentary rocks and it cleaves into transparent sheets. It is readily transformed into clay by weathering. Owing to their high potassium content (KAl2(AlSi3O10)(OH)2), these minerals are good fluxes. They are conducive to liquid phases at low temperatures (950°C). Their sintering interval is short (Kirkpatrick 1983). Furthermore, hematite compounds also act as fluxes in a clay body during the firing process (Anthony et al. 2011). Clay bodies undergo several changes during drying and firing stages as a result of physical, chemical and mineralogical modifications. Kaolinite–illite is the most widely used clay mixture in the ceramic industry. Illite is one of the main clay phases used for the preparation of mixtures for traditional ceramics.
Hydrothermal alteration mineralogical footprints for New Zealand epithermal Au-Ag deposits
Published in New Zealand Journal of Geology and Geophysics, 2019
Mark P. Simpson, Antony B. Christie
Illite generally occurs in strongly altered rocks and illite-smectite in strongly and moderately altered rocks. Both these clays occur as alteration products of plagioclase, adularia and albite (Figures 4 and 6). The extent to which adularia and albite are altered to illite or illite-smectite is highly variable (<5 to >95%; commonly >30%), and often can be overprinted by later calcite. Smectite is present in strongly, moderately and weakly altered rocks. In weakly altered volcanic rocks, glass, amphibole, pyroxene and plagioclase incipiently along fractures, are altered to smectite. In moderately to strongly altered volcanic rocks, plagioclase is more strongly altered to smectite (Figure 4).