Mass change, petrography and damage ratings of bars at the completion of the concrete microbar test
Bibliographic record
Abstract
During the course of the concrete microbar test the mass changes of the bars were measured at the same time as the lengths. The mass changes of the bars are characteristic of the petrography of the aggregates. Microbars made with 'inert' alumina grinding balls showed continuous mass gain for 50 days, but virtually no expansion. In contrast, microbars containing 50% opal and a non-reactive dolostone exhibited mass loss for about 10 days that was proportional to expansion. Thereafter, the mass loss leveled off. The gel formed by the reaction migrated into the NaOH solution where it precipitated. The greywackes and sandstones, in which microcrystalline quartz is the reactive component, exhibited a mass gain of about 0.4% in the first 8 days followed my mass loss. Only one unaltered volcanic rock, an andesite, was evaluated. It showed mass gain for 15 days but thereafter showed no significant change. Cristobalite is the main reactive component in the andesite. The mass change graphs of the gravels reflected the composition of the major component of the gravel. The damage rating indices (DRI's) were determined at the end of the tests. All the microbars showed extensive fine cracking, without gel, in the cement paste. This pattern of cracking is quite different from that observed in concrete prisms or in cores from field concretes. No correlation was found between the microcrystalline quartz content of many aggregates and expansion in the microbar test. The lack of correlation between expansion in the concrete prism and concrete microbar tests raises serious concerns about the advisability of using the results of the microbar test to evaluate the potential expansivity of aggregates for use in concrete without first confirming the results in a concrete prism 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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".