Early carbonation curing of fresh concrete and its applications in precast concrete production
Bibliographic record
Abstract
Carbonation curing of fresh concrete at early age and the feasibility to integrate the technology into precast concrete production were investigated. It was found that equilibrium of relative humidity between ambient environment and interior concretes was not possible to achieve in early carbonation of fresh concrete even with preconditioning. Instead, the degree of carbonation was dominated more by the water content in the concrete than by its internal humidity. A fan-drying precondition seemed to be necessary and practically feasible to justify the water content in industry scale application. The process was applied to the production of precast lightweight concrete panels and normal weight hollow core concrete slabs. The lightweight aggregates were utilized as internal water reservoirs to balance the moisture equilibrium during preconditioning, carbonation reaction and subsequent hydration. Water movement from the internal reservoirs was postulated by resistivity measurements; and was further verified in terms of CO2 uptake, strength development, plastic shrinkage compensation and alkalinity regain. A near-surface diffusion carbonation curing was developed to partially replace the heat curing in hollow-core concrete slab production. The hollow core slab so produced had shown much better strength than the hydration reference or by the heat curing alone, with reduced porosity and less vulnerability to delayed ettringite formation. Besides the technical benefits, CO2 sequestration potential is an added value to the process. An average 15% CO2 uptake could lead to sequestration of approximately 10,000 tonnes of CO2 per year by precast hollow-core concrete plants in Canada alone.
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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 | 0.001 | 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) | 0.001 | 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".