On the high stress compression of bentonites
Bibliographic record
Abstract
High stress consolidation tests (up to 30 MPa) were carried out on slurries made up of three bentonites considered as possible constituents for engineered clay barriers used for nuclear waste disposal at great depth (Na Kunigel, Na-Ca MX80 Wyoming clay, and Ca Fourges clay). Water retention curves (WRCs) were determined for a wide range of suctions (up to 305 MPa). A bilinear shape for the compression curves and the WRCs was observed in the three clays, with significant changes occurring in the 0.41 MPa suctionstress range. The permeability and the coefficient of consolidation were also determined during the compression tests. In the WRCs and compression curves, the two clays containing Na+ exhibited a similar behaviour, which was different from that of the Ca2+ clay. The coefficient of consolidation for the three clays was decreasing in the 0.41 MPa stress range and increasing at higher stresses. Data were interpreted in the light of existing experimental observations on the microstructural changes of similar swelling clays carried out by various authors, which obtained compatible and coherent results. The diffuse double theory, often used in the interpretation of the volume change behaviour of swelling clays, was also considered. Under higher stresses (> 2 MPa), the compressive behaviour appeared to be linked to the expulsion water molecules that form the hydration shells around exchangeable cations inside the domains formed of staked clay plates. The permeability properties of the Ca2+ and Na+ clays were linked to the microstructure features and to the WRCs, whereas the changes in the coefficients of consolidation during compression were linked to the changes in soil stiffness.Key words: consolidation, swelling clay, permeability, exchangeable cations, diffuse double layer, adsorbed water.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".