Carbonation front in cement paste detected by T 2 NMR measurements using a low field unilateral magnet
Bibliographic record
Abstract
Unilateral magnetic resonance was used to obtain the CPMG T 2 decay at different positions along 6 cm long cement paste samples. The aim was to detect the carbonation front based on changes in the pore structure caused by accelerated carbonation and to compare the results with the phenolphthalein test. Cement pastes at water-to-cement ratios of 0.60, 0.50, and 0.40 were prepared using ordinary Portland cement. After moist curing and conditioning at 65% RH and 35 °C, the pastes were subjected to accelerated carbonation with 4% by volume CO2 at 65% RH and 35 °C. Carbonation increases the magnetic resonance T 2 lifetime compared with the control and compared with the noncarbonated region of the samples. A reduction in porosity and changes in the pore size distribution are caused by carbonation. The position with the highest rate of T 2 change was consistent with the fully carbonated front determined by the phenolphthalein test.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".