A Test Method to Identify the Onset of Freeze-Thaw Deterioration in Masonry
Bibliographic record
Abstract
Our aging building stock provides tremendous opportunities to reduce our overall environmental footprint through upgrades to the exterior enclosure. It is often preferable to modify existing building enclosures rather than to replace them. Buildings with solid or load-bearing masonry walls typically employ interior insulation retrofit strategies as these buildings often have heritage significance that preclude work from the exterior. Adding insulation on the interior side of solid masonry walls may result in accelerated masonry freeze-thaw deterioration, embedded metal (lateral ties and supporting angles/structure) corrosion, and/or embedded wood joist rot. A limit states design approach is used extensively when designing structures but is still in its infancy for designing building enclosures. In general, limit states design consists of identifying material failure types and then making design decisions so that the probability of reaching the associated limit state is below a prescribed value. In masonry walls, the types of durability failure include freeze-thaw (or frost) damage, salt deterioration, corrosion of embedded metals, and wood rot. With respect to frost damage, the proposed pertinent material property limit is the Critical Degree of Saturation (Scrit) defined as the minimum moisture content of a brick unit at which internal damage may occur if the unit is subject to freeze-thaw cycling. This paper describes a method for determining the Scrit in brick masonry units using frost dilatometry. The process involves wetting specimens to various degrees of saturation, sealed in a manner to limit moisture loss, and then subjecting them to multiple freeze-thaw cycles. The change in length of the specimens following freeze-thaw testing is measured, expressed in terms of microstrain, and plotted against degree of saturation. Scrit is the lowest degree of saturation at which microstrain is greater than measurement error. Two methods may be used to identify if a material may exceed Scrit in service: hygrothermal modeling and maximum saturation coefficient. Hygrothermal modeling is a comparative approach suited for analyzing the change in frost damage risk when insulating existing historic masonry buildings. Maximum saturation coefficient is an expedient but conservative method that is most useful in assessing whether new brick should be used in severe weathering applications. Moving towards a limit states approach in assessing masonry durability has proven useful in practice for assessing whether a specific masonry unit type can safely be used in a severe weathering application and assessing materials and methods of insulating historic masonry buildings without unacceptably increasing the risk of frost damage.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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".