Shear Strength and Consolidation Characteristics of Calcium and Magnesium Illite

Abstract

In recent soil mechanics litcrature attempts have been made to explain the engineering properties of clays in terms of surface chemical theories, particularly the Gouy-Chapman theory. Experimental confirmation of these theoretical predictions have been restricted almost exclusively to studies performed on fine grain size fractions of montmorillonitc. it seemed d~sirable to determine experimentally the effect of physico-chemieal variables on the engineering properties of a more typical engineering material. The < 2/t fraction of Fithian illite was selected.A study was made of the effect of variations in the pore water electrolyte concentration on the engineering properties of homoionie Ca-and Mg-illite. Pore water electrolyte concentrations ranged from 1 N down to about 10 -4 N. Engineering tests included Atterberg limits, one-dimensional consolidation tests, and effective stress triaxial tests.The electrolyte concentration was found to have only a small effect on the Atterberg limits, the maximum limits occurring at electrolyte concentrations between 0.01 N and 0.1 iN. For virgin consolidation the soil seemed strongest at about the same range in electrolyte concentrations but the effect was not large. Electrolyte concentration had almost no effect on the position of the rebound (swelling) curves. The most important effect of electrolyte concentration seemed to be its effect on the geometric arrangement of the particles tor samples that were sedimented from dilute suspension. The geometric arrangement of particles seems to be a more significant variable than the osmotic repulsion between particles.There still appears to be merit in the old mechanical approach where the compression characteristics are explained by elastic bending (reversible), slippage (partially reversible), and rupture (irreversible) of particles. Double layer phenomena seem to exert a much smaller influence on the engineering properites of nonexpanding lattice clay minerals than is commonly inferred in the literature.

Effects of Adsorbed Cations on Physical Properties of Tropical Red Earths and Tropical Black Earths

“…The stabilities of Ca-and Mg-systems were weakly dependent upon salt concentrations. Olson and Mitronovas (1960) studied the engineering properties of homoionic Ca-and Mg-illites using Atterberg limits, one-dimensional consolidation tests, and effective-stress triaxial tests. In general they found the Atterberg limits plastic and liquid limits) of Ca-clays to be electrolyte concentration.…”

Exploring Shear Wave Velocity—NSPT Correlations for Geotechnical Site Characterization: A Review

“…The resonant column test can be subclassified into several techniques depending on the specimen-setup-boundary condition and the vibration mode. The most popular setups are the fixed-free end and free-free end resonant column to measure both the longitudinal and torsional specimen vibration, as developed by Wilson [51] and Hardin and Richart [33], respectively. Drnevich, in 1985 [52], combined the resonant column and torsional shear into one device to identify the elastic characteristic of geomaterial with a strain range of 10 −6 -10 −1 .…”