Swelling characteristics of bentonites in artificial seawater

Abstract

Bentonite is currently designated for use as a buffer material for the repository of high-level radioactive waste because such a material requires swelling characteristics to seal the waste. A high-level radioactive waste disposal facility may be built in a coastal area of Japan because transportation of this waste by ships is feasible. Therefore, it is important to investigate the effects of seawater on a bentonite-based buffer. This study is intended to investigate the influence of seawater on the swelling pressure and swelling deformation characteristics of five common types of bentonite. The experiments described herein clarify the relations between the influence of seawater grade and compaction density, type of exchangeable cation, montmorillonite content of the bentonite, and vertical pressure condition. Based on experimental results, suitable specifications have been defined for a bentonite-based buffer that can withstand the effects of seawater.

Influence of the Soil Fabric on the Mechanical Properties of Unsaturated Clays

“…Kunigel-V1 is a commercial sodium type bentonite from Yamagata, Japan, containing 48z to 57z montmorillonite (smectite mineral), with ratios depending on the deposit depth (Komine, 2004;Komine et al, 2009) and other non-swelling minerals, such as quartz, zeolite, and feldspar. NSF Clay is a commercially available non-swelling clay from Okayama, Japan, and is mainly composed of illite, with other minor minerals, such as quartz and feldspar.…”

“…There is a possibility that the strain rate employed in this investigation is not slow enough for water to move from one location to another, allowing for particle rearrangement. Komine and Ogata (1994,2004) and Komine et al (2009) have performed numerous studies to observe the swelling behaviour of Kunigel-V1. The testing methods employed required a testing period of one week, but swelling was observed within theˆrst day, meaning swelling was almost instantaneous.…”

Hydraulic conductivity and swelling ability of a polymer modified bentonite subjected to wet–dry cycles in seawater

“…Several investigations have been undertaken to evaluate the effect of wet and dry cycles combined with cation exchange on hydraulic conductivity and swelling ability of clay barriers (Hewitt and Philip, 1999;Lin and Benson, 2000;Bouazza et al, 2006Bouazza et al, , 2007Thiel et al, 2006;Komine et al, 2009;Rowe et al, 2011;Tang et al, 2011;De Camillis et al, 2014;Mukunoki et al, 2014;He et al, 2015).…”

Swelling pressure and hydraulic conductivity of compacted GMZ01 bentonite under salinization–desalinization cycle conditions

“…The influence of the permeant salinity on the intrinsic permeability of the granite/bentonite mixture has been highlighted by Villar (2006), as well as the swelling capacity of this mixture. This kind of alteration of clays due to the interaction with chemical fluids has been confirmed by numerous researchers in literature and found that the swelling pressure of bentonite decreases as the salinity of pore water increases (Karnland et al, 2006;Castellanos et al, 2008;Herbert et al, 2008;Komine et al, 2009;, and the hydraulic conductivity of bentonite increases as the concentration of infiltrating solution increases (Studds et al, 1998;Mata, 2003;Villar, 2005;.…”