Abstract. Collapsible soils are unsaturated soils which may undergo inter-granular rearrangement with abrupt and significant volume reduction after wetting. The large settlement resulting from the soil collapse pushed for deep studies of these types of soils. The experimental study consists to illustrate the influence of the salt concentration, compaction energy and moisture content on the change of microstructural characteristics of the reconstituted soil and reduction of the collapse potential.
The study of collapsible soils that are generally encountered in arid and semi-arid regions remains a major issue for geotechnical engineers. This experimental study, carried out on soils reconstituted in the laboratory, aims firstly to present a method of reducing the collapse potential to an acceptable level by treating them with different levels of bentonite–cement mixture while maintaining the water content and degree of compactness, thus reducing eventual risks for the structures implanted on these soils. Furthermore, a microscopic study using scanning electron microscopy was carried out to explore the microstructure of the soil in order to have an idea of the phenomena before and after treatment. The results show that treatment with a bentonite–cement mixture improves the geotechnical and mechanical characteristics, modifies the chemical composition of the soil, reduces the collapse potential and the consistency limits. The microstructural study and the X-ray energy dispersive spectroscopy analysis clearly illustrate an association of elementary particles in the soil aggregates, whereby the arrangement of these aggregates leads to the formation of a dense and stable material.
Abstract. Collapsible soils are unsaturated soils which present a potential for large strains and a complete change to the whole particle structure after wetting with or without loading. These soils are characterized with loose structures composed of silt to fine-sand-size particles.The objective of this experimental study is to illustrate that the resistance of collapsible soil can be improved. This study demonstrates that it is possible to minimize the collapsible potential Cp to an acceptable level after chemical treatment with salt (sodium chloride NaCl) at different concentrations (0.5, 1.0, 1.5 and 2.0 mole/liter) and at different compaction energies. The method used in this study is based on oedometric tests with variable normal stresses.
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