Durability and Cold Temperature Performance of SBS-Modified Bituminous Roofing Membranes
Bibliographic record
Abstract
The National Research Council of Canada, in collaboration with a Canadian roofing manufacturer, conducted an experimental program to evaluate the durability of SBS-modified bituminous roofing membranes in Canada. This study examined the effect of heat aging on the mechanical and chemical properties of nine commercially available SBS-modified membranes, with emphasis on cold temperature performance. These membranes varied in reinforcements and densities, and were selected to be representative of SBS-modified membranes currently used in Canada. The membrane samples were heat aged in convection ovens at 70±3°C for six months. During this process, some samples were withdrawn at two-month intervals and their tensile properties at 23°C and -30°C, cold flex temperature and glass transition temperature determined. The results confirmed that heat aging mainly affected matrix-controlled properties of the membranes. In addition, the reinforcement controlled the mechanical properties at 23°C but the modified bitumen governed the failure mechanism at -30°C for the polyester reinforced membranes.
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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 | 0.000 |
| 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) | 0.001 | 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".