Alkali-carbonate reaction in concrete - Microstructural consequences and mechanism of expansion
Bibliographic record
Abstract
A detailed microstructural investigation of a concrete expanding due to alkali‑carbonate reaction (ACR) shows that the cement paste adjacent to reactive aggregate particles is carbonated, which leads to a sulfur redistribution resembling internal sulfate attack. Simultaneously to dedolomitization, partial dissolution of illite occurs in aggregate particles leading to the formation of brucite, hydrotalcite, magnesium-silicate-hydrate (M-S-H) and calcium‑aluminum-silicate-hydrate (C-A-S-H), in addition to calcite and thus to a substantial increase in solid volume. Thermodynamic modelling indicates that the simultaneous presence of illite and dolomite can accelerate the reactions within the aggregates. No alkali-silica reaction (ASR) products are observed. Dolomite, illite and all reaction products display a negative ζ-potential at high pH generating repulsive forces during dedolomitization. Together with the substantial increase in molar volume, the concrete expansion can be mainly attributed to the solidification pressure of hydrotalcite and M-S-H formation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".