The osmotic, hydraulic and self-healing efficiency of bentonite based barriers (e.g. geosynthetic clay liners) for containment of polluting solutes are governed by both the chemico-physical intrinsic parameters of the bentonite, i.e. the solid density (rosk), the total specific surface (S), the fixed negative electric surface charge (sigma), the Stern fraction (fStern), and by the chemico-mechanical state parameters able to quantify the solid skeleton density and fabric, i.e. the total (e) and nano (en) void ratio, the average number of platelets per tactoid (Nl, AV), and the effective electric fixed-charge concentration (csk,0). In turn, looking at saturated active clays only, the state parameters seem to be controlled by the effective stress history (SH), ionic valence (vi) and related exposure sequence of salt concentrations in the pore solution (cs). A theoretical framework, able to describe chemical, hydraulic and mechanical behaviors of bentonites in the case of one-dimensional strain and flow fields, has been set up. In particular, the relationships, linking the aforementioned state and intrinsic parameters of a given bentonite with its hydraulic conductivity (k), effective diffusion coefficient (D*s), osmotic coefficient (w) and swelling pressure (usw) under different stress-histories and solute concentration sequences, are presented. The validity of the proposed theoretical hydro-chemico-mechanical framework has been tested by comparison of its predictions with some of the available experimental results on bentonites (i.e. hydraulic conductivity tests, swelling pressure tests and osmotic efficiency tests).
Intrinsic and state parameters governing the efficiency of bentonite barriers for contaminant control / Dominijanni, Andrea; Manassero, Mario; Boffa, Giacomo; Puma, Sara. - STAMPA. - (2017), pp. 45-56. (Intervento presentato al convegno International Workshop on Advances in Laboratory Testing and Modelling of Soils and Shales, ATMSS 2017 tenutosi a Villars-sur-Ollon, Switzerland nel 18-20 January 2017) [10.1007/978-3-319-52773-4].
Intrinsic and state parameters governing the efficiency of bentonite barriers for contaminant control
DOMINIJANNI, ANDREA;MANASSERO, Mario;
2017
Abstract
The osmotic, hydraulic and self-healing efficiency of bentonite based barriers (e.g. geosynthetic clay liners) for containment of polluting solutes are governed by both the chemico-physical intrinsic parameters of the bentonite, i.e. the solid density (rosk), the total specific surface (S), the fixed negative electric surface charge (sigma), the Stern fraction (fStern), and by the chemico-mechanical state parameters able to quantify the solid skeleton density and fabric, i.e. the total (e) and nano (en) void ratio, the average number of platelets per tactoid (Nl, AV), and the effective electric fixed-charge concentration (csk,0). In turn, looking at saturated active clays only, the state parameters seem to be controlled by the effective stress history (SH), ionic valence (vi) and related exposure sequence of salt concentrations in the pore solution (cs). A theoretical framework, able to describe chemical, hydraulic and mechanical behaviors of bentonites in the case of one-dimensional strain and flow fields, has been set up. In particular, the relationships, linking the aforementioned state and intrinsic parameters of a given bentonite with its hydraulic conductivity (k), effective diffusion coefficient (D*s), osmotic coefficient (w) and swelling pressure (usw) under different stress-histories and solute concentration sequences, are presented. The validity of the proposed theoretical hydro-chemico-mechanical framework has been tested by comparison of its predictions with some of the available experimental results on bentonites (i.e. hydraulic conductivity tests, swelling pressure tests and osmotic efficiency tests).Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/11583/2672645
Attenzione
Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo