Comparison of expansions in the concrete prism and concrete microbar tests of an assorted suite of aggregates from several countries
Bibliographic record
Abstract
The usefulness of accelerated test methods for AAR, such as the mortar bar test ASTM C-1260, the various autoclave tests and the proposed Chinese concrete microbar test (RILEM AAR-5) depends on their being reasonable correlation between expansion in the concrete prism test and in the accelerated tests. Results of concrete prism tests run at 38°C are widely regarded as providing the best correlation with the performance of field concrete. The protocol for the concrete microbar test is similar to that of ASTM C 1260 except that the aggregate grading is 12.5 mm to 4.75 mm, the bar size is 40 x 40 x 160 mm and the mixture proportions are one part portland cement to one part aggregate. The concrete microbar test that was originally developed for the evaluation of alkali-carbonate reactive aggregates has been found to also be effective with alkali-silica reactive aggregates. A number of assorted aggregates from several countries were selected for evaluation in the concrete microbar test and in the concrete prism test (CSA A23.2-14A). The test results for siliceous limestones showed that there is good correlation between expansion in this test and in the concrete prism test. The proposed expansion limit is 0.09% at 30 days. No correlation was found between expansions in the two test methods for assorted siliceous aggregates including greywackes, sandstones, volcanic rocks, gravels and cataclastic rocks. However, aggregates in bars showing less than 0.04% expansion at 30 days were classed as innocuous in the concrete prism test. In the microbars, made with all the aggregates tested to date, expansion has been linear. This would permit estimation of the 30-day expansion by extrapolation from expansion at earlier ages. Opal exhibited no pessimum proportion in the concrete microbar test. Expansion was proportional to the percentage of opal added to an innocuous aggregate.
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".