Alkali thresholds in concrete; the balanced alkali approach in ASR mitigation
Bibliographic record
Abstract
The Alkali Silica Reaction (ASR) is a deleterious reaction in concrete that poses significant durability\nconcern worldwide. As a preventative measure, total alkali content of general purpose Portland cements\ncan be limited. In Australia, like in other countries, general purpose cement is limited with a conservative\nalkali content of 0.6%, this may be unnecessary, as low risk non-reactive aggregates and SCM blends\nare effective in reducing ASR prevalence. Indeed there is a growing argument to transition to risk\nassessed methods in choosing cement alkali levels. ASTM in the USA has employed a prescriptive\napproach to selecting preventative measures that incorporates a variety of cement alkali contents\nwithout compromising on safety. Similar balanced alkali approaches such as those recommended in\nEurope, Canada and New Zealand may be applicable in Australia. Raising alkali limits to a level greater\nthan 0.6% in cement used in conjunction with alternative mitigation techniques would reduce the\neconomic and environmental impact associated with alkali removal during cement production. This\nliterature review discusses the Australian approach to alkali limits in contrast to the methods used\naround the world and explores the continuing research into alkali’s mechanistic contribution to ASR.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".