Cold weather protection requirements for a low strength repointing mortar
Bibliographic record
Abstract
This paper assesses whether the 28-day protection period for a low strength Portland cement/lime repointing mortar before exposure to freezing temperatures could be reduced. This requirement, by the Heritage Conservation Directorate at Public Works & Government Services Canada, was used for repointing mortars in the conservation of historic masonry. The performance of the mortar was evaluated for frost durability in accelerated laboratory testing as well as some testing at an outdoor exposure site. The mortar was tested as part of small sandstone masonry prisms to more realistically simulate practice. An interim recommendation is that the protection period can be reduced to 7 days. During the first three days the mortar should be damp cured using damp burlap covered with plastic at a masonry temperature above 10°C. This is followed by 4 additional days of protection from wind and precipitation with the masonry temperature above 0°C. Further tests to assess lower curing temperatures and possible longer protection periods against precipitation, and field experience with repointed mortar joints are needed before firmly adopting these recommendations. They should not be taken as a green light for construction in winter. Repointing of mortar joints during periods when freezing conditions may occur should be discouraged, but can be inevitable if projects run late or unusual weather conditions occur.
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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 | 0.002 |
| 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) | 0.003 | 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".