Differences in the production-related properties of the three primary clay minerals kaolinite-illite-montmorillonite (Part 2)

»1 SiO₄ tetrahedra and Al(O,OH)₆ octahedra as building blocks in layer lattice silicates according to [4]

»2 Layer structure of the montmorillonite according to [5]

»3 Particle size histogram of the main clay minerals and their varieties

»4 Cumulative undersize curves of the main clay minerals and their varieties

»5 Electron microscope images of clay minerals according to [10]a) Well-formed hexagonal kaolinite plateletsb) Kaolinite platelets in a “stack of coins”c) Severely weathered kaolinite (fireclay)d) Seladonitee) Illitef) Fine-grained montmorillonite

»6 Differential thermal analysis of clay minerals

»7 Dilatometer curves of mica and mica-like clay minerals

»8 Mass loss curves of the clay minerals aged at 20° C and 60% humidity

»9 Temperature-dependent coefficients from statistical analysis for firing shrinkage of clay mineral varieties after firing

»10 Temperature-dependent coefficients from statistical analysis for flexural strength of clay mineral varieties after firing

»11 Temperature-dependent coefficients from statistical analysis for water absorption of clay mineral varieties after firing

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drittes 5

On account of their different crystal structures, the primary clay minerals kaolinite, illite and montmorillonite exhibit different material properties and behaviour in production processes. Owing to the different formation and rearrangement of the strata, often two or three varieties of the respective primary clay minerals are encountered, which differ in their particle size and chemical composition. The results of statistical analyses on a large number of brick raw materials and bodies are presented in two parts, which reveal the differences in the shaping, drying and firing behaviour of the clay mineral varieties and document these numerically.

4 Shaping properties

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In German-speaking countries, in the ceramic laboratory, the mixing water requirement is often determined according to Pfefferkorn, at a deformation ratio of 2. The mixing water requirement is...

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Issue 01/2022

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Issue 04/2014

Differences in the production-related properties of the three primary clay minerals kaolinite-illite-montmorillonite (Part 1)

1 Introduction Nanotechnology and nanopowders have become very popular terms today. There is, however, one raw material that has been used for thousands of years and whose special properties are...

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Methods of evaluation for raw material suitability and body optimization (Part 1)

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Issue 04/2014

Causes and avoidance of firing-related damage Part 2: Strength-reducing reactions in the heating-up zone from 500 to 800° C

4 Expansion and shrinkage processes In a tunnel kiln firing process for heavy clay products, there should be no mutual contact between the wares to be fired, and all exposed surfaces within and around...