Diffusivity of CO<sub>2</sub> in Bitumen: Pressure–Decay Measurements Coupled with Rheometry
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Bibliographic record
Abstract
The combined pressure-decay technique with rheometry is developed to measure the diffusivity of carbon dioxide (CO 2 ) in bitumen at temperatures of 30, 50, and 70 °C and pressures of 2 and 4 MPa. Mixing due to shear imposed by a rheometer allows rapid direct measurement of the equilibrium pressure in CO 2 –bitumen systems accurately. The comparison of the measured equilibrium pressures with the values obtained from the data regression demonstrates significant discrepancies, which can lead to a great deviation in the diffusivity, up to 5-fold different than the true values. The measured values for the diffusivity of CO 2 into the bitumen increase with temperature, following the Arrhenius equation. By changing the temperature from 30 °C to 70 °C, the diffusivity increases by 88% at 2 MPa and 54% at 4 MPa. The diffusivity also increases with the pressure, suggesting the ease of diffusion at the presence of the CO 2 molecules in the liquid phase. The effect of pressure is more dominant at lower temperatures while the diffusivity increase is 53% at 30 °C, compared to 25% at 70 °C. Furthermore, the findings demonstrate that the CO 2 –bitumen system does not follow any constant pattern in the diffusivity–viscosity–temperature relationships, which is due to the ongoing phase change at the studied temperature range.
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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 it