Despite the increasing understanding of bentonite behaviour, there is still missing evidence on how different hydro-mechanical loadings, including sequences of hydration and compression, affect the fabric and the volume change behaviour of the material. It is generally assumed that the interplay between the behaviour of clay assemblages and the overall fabric of the material is the reason of having final states that are dependent on the stress path followed. Here the results of an experimental campaign aiming to study these factors are reported and discussed. Free swelling and swelling pressure tests were performed, both followed by compression to a relatively high stress. The experimental program involved various samples that were dismantled at intermediate states in order to perform microstructural observations by means of mercury intrusion porosimetry and electronic scanning microscopy. It was observed that while the void ratio at a given stress level depends on the stress path, subsequent compression led to a unique virgin compression line. The data obtained at the microscale gave further insight for an interpretation of the volume change behaviour observed at the macroscale, showing that at high stress the material tends to recover the same fabric regardless of the path to saturation.
A b s t r a c tThe results of laboratory tests and geotechnical view on sands hydrophobized by alkoxysilane emulsions are presented. For the soils subjected to this process, very low permeability and no capillary elevation was observed. Laboratory tests also indicate that other physical and mechanical properties of hydrophobized sands remain nearly untouched, i.e., the considered hydrophobisation process does not reduce the strength of soils. Properly composed alkoxysilane emulsions can also solidify in pores to produce a stabilizing silicate binder. The filtration barriers in ground and soil stabilization are thus considered as possible applications of the hydrophobized soils. The process of treatment of granular soils with alkoxysilanes is neutral for the environment and the cost of implementation of the method is relatively low.
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