Novel procedure for the estimation of swelling pressures of compacted bentonites based on diffuse double layer theory

• Published in: Environmental earth sciences Vol. 70; no. 1; pp. 303 - 314
• Main Authors: Bharat, Tadikonda Venkata, Sivapullaiah, Puvvadi Venkata, Allam, Mehter M
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2013; Springer Berlin Heidelberg; Springer; Springer Nature B.V
• Subjects: Backfill; Bentonite; Biogeosciences; Clay; Compacting; Diffusion; Diffusion layers; Double layer; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Electric potential; Engineering and environment geology. Geothermics; Environmental Science and Engineering; Exact sciences and technology; Geochemistry; Geoengineering; Geology; Geotechnology; hazardous waste; Hydrology/Water Resources; Original Article; Pollution, environment geology; Radioactive wastes; Swelling; swelling (materials); Terrestrial Pollution; Void ratio; Diffuse double layer theory; Bentonite clays; Swelling pressures; Gouy–Chapman method; Gouy―Chapman method; density; accuracy; bentonite; swelling; pressure; high-level waste; electrolytes; pollution; radioactive waste; clay; sedimentary rocks; backfill; theoretical studies; theory; clastic rocks
• DOI: 10.1007/s12665-012-2128-7
• ISSN: 1866-6280

Bentonite clays are proven to be attractive as buffer and backfill material in high-level nuclear waste repositories around the world. A quick estimation of swelling pressures of the compacted bentonites for different clay–water–electrolyte interactions is essential in the design of buffer and backfill materials. The theoretical studies on the swelling behavior of bentonites are based on diffuse double layer (DDL) theory. To establish theoretical relationship between void ratio and swelling pressure (e versus P), evaluation of elliptic integral and inverse analysis are unavoidable. In this paper, a novel procedure is presented to establish theoretical relationship of e versus P based on the Gouy–Chapman method. The proposed procedure establishes a unique relationship between electric potentials of interacting and non-interacting diffuse clay–water–electrolyte systems. A procedure is, thus, proposed to deduce the relation between swelling pressures and void ratio from the established relation between electric potentials. This approach is simple and alleviates the need for elliptic integral evaluation and also the inverse analysis. Further, application of the proposed approach to estimate swelling pressures of four compacted bentonites, for example, MX 80, Febex, Montigel and Kunigel V1, at different dry densities, shows that the method is very simple and predicts solutions with very good accuracy. Moreover, the proposed procedure provides continuous distributions of e versus P and thus it is computationally efficient when compared with the existing techniques.