One concept that appears at the end of Chapter 1 of Soils in Construction is that of the specific surfaces of soil materials, including data from Lambe and Whitman’s classic text Soil Mechanics. Additional information on this topic can be found in Tsytovich, which is reproduced below. (Tsytovich refers to this as “unit surface area,” but the concept is the same.)
A factor of importance in the evaluation of the properties of solid soil particles is their mineral composition. Thus, some minerals, such as quartz and feldspar, interact only slightly with the surrounding water, whereas other minerals, for instance, montmorillonite, can interact substantially more actively and in a different way. The smaller the particles of a soil, the greater their unit surface area (per cm3 or per gram) and the larger the number of centres of interaction with the surrounding water and in contacts between solid particles proper. For instance, particles of kaolin (a clay mineral) have a unit surface area of 10 m2/g, whereas those of montmorillonite have a very large unit surface area of 800 m2/g, which inevitably affects the properties of natural soils containing particles of montmorillonite. The presence of particles of mica (which are very slippery and have only a negligible shear resistance) has an essential effect on the physical properties of the soils containing such particles; this circumstance must always be taken into account.
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