Mechanical and Microstructural Properties of Cemented Paste Backfill with Chloride-Free Antifreeze Additives in Subzero Environments
Bibliographic record
Abstract
Cement paste backfill (CPB) is an innovative technology of recycling mine waste (tailings) into construction materials to increase mine safety and productivity and promote sustainable mining. However, the application of CPB technology in mines located in cold or permafrost areas has been difficult due to freezing temperatures. These subzero temperatures can cause fresh CPB to freeze while being transported through the pipelines, which has significant financial implications for the mine. To overcome these problems, antifreeze additives are added to the CPB during its mixing or preparation to enhance the rheological properties of fresh CPB. The addition of antifreeze additives in CPB is an inexpensive and easy-to-operate method currently known to ensure its smooth delivery in subzero environments. But the mechanical and microstructural characteristics of CPB with chloride-free antifreeze additives in subzero conditions are not well understood. Therefore, this study experimentally examined the mechanical (strength, deformation behavior) and microstructural properties of CPB containing chloride-free antifreeze additives and cured under subzero conditions. Three kinds of chloride-free antifreeze (calcium nitrate, calcium nitrite, and urea) with different concentrations (0, 5, 15, and 35 g/L) were separately added to the CPB samples curing at different subzero environments (−1°C, −6°C, and −12°C) for different ages (7, 28, 60, and 90 days). The uniaxial compressive strength (UCS) tests, a series of microstructural (XRD, MIP, DT/DTG, SEM) analyses and monitoring (suction, volumetric water content) experiments of CPB were performed. The obtained results showed that the addition of antifreeze weakened the mechanical properties of CPB. Furthermore, the UCS of CPB was significantly affected by the antifreeze type, antifreeze concentration and subzero curing temperature. The findings in this research will support the successful application of antifreeze cemented backfill technology in cold regions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".