Insight on the Void Ratio–Suction Relationship of Compacted Bentonite during Hydration

Abstract

Investigation on swelling characteristics of buffer/backfill materials during hydration is an important issue in the design of artificial barriers in high-level radioactive waste (HLW) disposal repositories. In this work, for clarifying the characteristic of void ratio–suction relationship for compacted bentonite on hydration path, suction-controlled swelling deformation tests under constant vertical stresses 0.001~40 MPa were carried out on compacted bentonite specimens. Four different types of void ratio-suction curves indicated that swelling-collapse behavior under hydration depends on suction and over-consolidation ratio (OCR), based on which the swelling index was defined. Then, equations were proposed for describing the swelling-collapse characteristic of void ratio–suction curves. Simulation results of suction-controlled swelling deformation tests show that the different types of the hydration deformation curves could be well described by the proposed equations. Obviously, the proposed equations could be used for description and prediction of swelling characteristics of compacted bentonite during hydration, which is also of great importance for the safety assessment of the HLW repositories.

Special Issue: Advancement of Functionalized Mineral Materials and Rock

“…The physical and mechanical behaviour, fracture, damage, and evolution processes of geomaterials under various environmental and mechanical conditions, such as thermal, mechanical, chemical, and electrical environments [6][7][8][9][10][11][12][13][14][15][16][17]20,21].…”

“…This Special Issue covers numerous aspects of functional mineral research. These topics focus on various themes, including the analysis of mineralogical composition and its effects on the physico-mechanical properties of geomaterials, the investigation of the impact of triaxial stress on the damage creep behaviour of geomaterials, and the evaluation of the thermophysical and mechanical characteristics of rocks under high-temperature circumstances [6][7][8][9][10][11][12][13][14]. The research conducted on these topics also involves various experimental and numerical techniques, such as digital image processing, Discrete Element Method (DEM), and analytical solution and simulation [13,[15][16][17][18].…”

“…These topics focus on various themes, including the analysis of mineralogical composition and its effects on the physico-mechanical properties of geomaterials, the investigation of the impact of triaxial stress on the damage creep behaviour of geomaterials, and the evaluation of the thermophysical and mechanical characteristics of rocks under high-temperature circumstances [6][7][8][9][10][11][12][13][14]. The research conducted on these topics also involves various experimental and numerical techniques, such as digital image processing, Discrete Element Method (DEM), and analytical solution and simulation [13,[15][16][17][18]. Moreover, several research studies have explored the feasibility of utilising organic waste materials, including red mud, bauxite tailings, and zeolite, as prospective building materials or sorbents to eliminate petroleum substances from paved surfaces [8,14,19].…”

“…Under constant vertical stress, Wang et al [13] conducted suction-controlled swelling deformation experiments on compacted bentonite specimens. Four typical void ratiosuction curve morphologies were observed, each revealing distinct swelling-collapse behaviour based on the suction and OCR (over-consolidation ratio).…”

Insight on the Swelling Pressure–Suction Relationship of Compacted Bentonite during Hydration

“…Compacted bentonite has emerged as a preferred choice for buffer/backfill materials in the disposal of high-level radioactive waste in numerous countries thanks to its low hydraulic conductivity, microporous structure, good sorption properties, and swelling capacity [1][2][3][4][5][6][7]. MX-80 bentonite extracted from Wyoming, USA, has been used in many disposal concepts in Sweden, Finland, Germany, and France.…”