Exploration of Clay and Shale Deposits in Ontario for Use as Supplementary Cementitious Materials
Bibliographic record
Abstract
To address the increasing shortage of conventional supplementary cementitious materials (SCMs) and promote sustainable concrete practices in Ontario, this study investigates the potential of various clay and shale deposits across Ontario for use as SCMs. These deposits include two kaolinitic clays from the Mattagami Formation in Northern Ontario and an illitic shale from the Georgian Bay Formation in Toronto. This study first evaluates the chemical reactivity of three common clay minerals, i.e., illite, kaolinite, and montmorillonite, when calcined at various temperatures. Their reactivity, along with interactions with limestone (calcite), was assessed using the rapid, relevant, and reliable (R3) test methods in accordance with ASTM C1897. The results indicate that the R3 reactivity of calcined clay minerals is directly proportional to the number of hydroxyl groups in their original mineral structures, with kaolinite showing the highest reactivity, followed by montmorillonite, and illite showing limited reactivity upon calcination. Furthermore, calcite particles not only contribute to the formation of monocarbonate (C4AcH11) but also promote its uniform distribution within the system. Two Hudson Bay Lowlands clay samples were collected from the Lower Mattagami River in Northern Ontario. The clays, composed of approximately 60-70 wt% kaolinite, exhibited enhanced R3 reactivity when calcined between 600 ºC and 900 ºC. The calcined clays are suitable for use in limestone calcined clay cement (LC3), as demonstrated by the higher compressive strengths of their LC3 mortar mixtures relative to the control mixture. The Georgian Bay shale sample was collected from a shaft excavation in Toronto. The shale, composed of approximately 67 wt% illite, was processed by calcination and by mechanochemical activation using an energy-intensive attrition mill. The mechanochemically activated shale exhibited a noticeable increase in R3 reactivity compared to the calcined shale. When incorporated into mortar mixtures, it had less negative impact on workability, primarily due to its re-adsorbed surface moisture, which offset the increased water demand in blended cements. These mortar mixtures also developed higher compressive strengths compared to the control mixture. The illitic shale activated using the attrition mill highlights its great potential as an SCM for future industrial applications.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".