Influence of age on masonry bond strength and mortar microstructureThis article is one of a selection of papers published in this Special Issue on Masonry.
Bibliographic record
Abstract
The effect of age on bond strength and mortar microstructure was investigated as part of an ongoing masonry bond strength research program at The University of Newcastle. Previous work has shown that both strength losses and strength gains occur with age. The potential loss of bond strength with time has structural implications as the design of masonry using the Australian masonry standard AS 3700–2001 is based on the 7 d bond strength. In this investigation, a single mortar-and-unit combination (dry pressed clay and 1:1:6 mortar) cured under ambient laboratory conditions was studied. Bond strength was determined at ages ranging from 3 to 365 d using a small-scale uniaxial tension test. Maximum bond strength was observed to occur at 180 d with strength minima occurring at 90 and 365 d. Scanning electron microscopy and X-ray diffraction techniques were used to further identify the mortar constituents and hydration levels. Changes in the density of the paste microstructure were observed up to 28 d, which correlated with the initial increase in bond strength. No other microstructural change to account for the strength variations between 28 and 365 d could be observed using these techniques.
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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) | 0.000 | 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) | 0.002 | 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".