Combined effect of mineralogical and chemical parameters on swelling behaviour of expansive soils

Abstract

Microlevel properties such as mineralogical and chemical compositions greatly control the macro behaviour of expansive soils. In this paper, the combined effect of mineral (i.e. montmorillonite, MMC) and chemical contents (i.e. Ca and Na in their total (T), leachable (L) and exchangeable form (CEC)) on swelling behaviour is investigated in a comprehensive way. Several 3-dimensional (3D) graphs correlating MMC and Ca/Na ratio, together, with swelling property (swelling potential, Sa, and swelling pressure, Sp) are developed. 3D plots, in general, portrayed a non-linear relationship of Sa and Sp with MMC and Ca/Na ratio, together. It is hypothesized that swelling initially is triggered by chemical parameters due to their quick and rapid ionization capability, but the overall swelling phenomenon is largely controlled by MMC. It is importantly found that expansive soils are dominant with divalent Ca++ ions up to MMC of 67% and beyond this percentage, monovalent Na+ ions are prevalent. From the interpretation of results, the maximum Sa of 18% and Sp of 93 kPa is measured at MMC of 43%, (Ca/Na)T of 10–14 and (Ca/Na)L of 2–7. It is concluded from study that total CEC + MMC for determining Sa and (Ca/Na)T + MMC for determining Sp are superior parameters to be considered. The findings of the study also excellently endorsed the results of Foster32, who stated that ionization of Na or Ca depends on the constituent mineral contents. The findings presented herein are unique, interesting and bear very practical significance, as no earlier research work reported such findings by accounting for chemical and mineralogical parameters impact, in tandem, on swelling properties.

Problems with reinforced concrete industrial floors with regard to subsoil swelling

“…Methods for determining the swelling potential of the soil can be divided into the following groups: Mineralogical identification -the mineralogical composition has a considerable influence on the swelling of soils and is therefore important for the description of the swelling potential and the soils themselves, e.g. [6][7][8][9]. However, from the point of view of geotechnicians and engineering geologists, mineralogical identification methods are uneconomical and impractical.…”

Conceptual Model of Expansive Rock or Soil Swelling

“…Numerous recent studies investigated the shrinkage and swelling of soils and desiccation cracking [40][41][42][43][44][45][46][47][48][49].…”

Effects of type and distribution of clay minerals on the physico-chemical and geomechanical properties of engineered porous rocks

“…These minerals have a significantly impact on the properties of porous media, therefore it is worthwhile to understand their effect on both technical industry and scientific research 21 . Such materials are characterized by strong adsorption capacity, large surface area and high swelling capacity 22 – 25 . These minerals are a subgroup of anisotropic phyllosilicates (one of the main groups of aluminosilicates) containing an octahedral (O) alumina and one or two tetrahedral (T) silica sheets, which together form a basic unit consisting of either 2:1 tetrahedral-octahedral-tetrahedral (TOT) or 1:1 tetrahedral-octahedral (TO) layers 26 , 27 .…”