Estimation of water retention behaviour of bentonite based on mineralogy and mercury intrusion porosimetry tests

Abstract

This paper develops a water retention model based on the soil mineralogy and microscopic features of the material behaviour. The model estimates the water content at a given total suction as the sum of the bentonite minerals interlayer water and the water in the interparticle pores. The paper proposes simple formulae to estimate the interlayer water content and interlayer void ratio based on mineralogical properties. Additionally, the model uses the mercury intrusion porosimetry measurements to approximate the water content in the larger pores. The validation of the proposed procedure relies on published data for MX-80 and GMZ bentonites and yields promising results. Even though the discussion and the validation are restricted to bentonite here, the procedure is generic in nature and can be modified easily for other geomaterials. The paper also offers insights into the links between soil microstructure and its macroscopic behaviour. The contribution provides a new tool for quick indirect estimation of the water retention behaviour of porous materials with known mineral composition and available microstructural data, e.g. based on the mercury intrusion porosimetry tests. Such tool is of high practical interest in design e.g. nuclear waste repositories where large material pool may be initially considered.

NMR–based experimental study on basic physicomechanical properties of saline clay

“…9, it can be seen that the pore size before and after shear was significantly increased due to the chemical action of the salt solution, which is consistent with the experimental results of Yu and Tian (2019); the overall pore size became smaller after experiencing the shear action. There are significant differences in the interval of microscopic porosity for different types of soils, and a large number of studies have shown that clayey soils are often categorized according to the pore scale into microscopic micropores (pores between lamellar clay particles in the range of 1.2 nm or 0.4 Å -12 Å; intra-aggregate pores in the range of 12 Å -200 nm), and macropores (inter-aggregate pores greater than 200 nm) (Abed and Sołowski. 2021;Seiphoori et al 2014).…”

Modelling the behaviour of unsaturated non-active clays in saline environment

“…The understanding of microstructure evolution when the water content and the chemical concentration of salts change, is fundamental for an accurate replication of unsaturated clayey soil behaviour, as the microstructure changes directly affect macroscopic properties, such as water retention curve, see e.g. Della Vecchia et al, 2019, Abed andSołowski, 2021. As evidenced by ESEM (Environmental Scanning Electron Microscopy) and MIP (Mercury Intrusion Porosimetry) tests, compacted clay microstructure may consist of clay clusters or aggregates (see Figure 1). After preparation, soil microfabric evolves with water content, as shown by, among others, Lloret et al (2003) and Romero et al (2011) for compacted clayey soils and Monroy et al (2010) for reconstituted specimens.…”

Fabric Investigation of Natural Sensitive Clay from 3D Nano- and Microtomography Data

“…Methods from materials science, such as scanning and transmission electron microscopy (SEM/TEM), mercury intrusion porosimetry (MIP), and wide or small angle X-ray or neutron scattering (W/SAXS, SANS) (e.g., Glatter and Kratky 1982;Toer and Reimer 1998;Giesche 2006) have been introduced in geomechanics to further probe clays at microscale despite their inherent limitations for use in fine-grained materials (Yao and Liu 2012;Deirieh et al 2018). The ultimate aim is to link the micro and macro response (e.g., Pusch 1970;Delage and Lefebvre 1984;Djéran-Maigre et al 1998;Hicher et al 2000;Ringdal et al 2010;Delage 2010;Hattab and Fleureau 2011;Hattab et al 2013;Suuronen et al 2014;Wensrich et al 2018;Birmpilis et al 2019;Cotecchia et al 2019;Delage and Tessier 2021;Abed and Sołowski 2020;Schuck et al 2020;Dor et al 2020;Zhao et al 2020). Regardless of the experimental method, either a bulk response of the complete sample volume (MIP, W/SAXS, SANS), a twodimensional (2D) map of the integrated response along the transmitted X-ray/electron beam (scanning W/SAXS and TEM), or a 2D surface profile (with a certain depth of view) is obtained (SEM).…”