Experimental investigation of hygro-thermo-fracture couplings in cement paste with mineral fillers via micro-scale splitting tests
Bibliographic record
Abstract
The fracture mechanics of heterogeneous cement paste with a low water-to-cement (w/c) ratio under varying relative humidity (RH) and temperature (T) is critical for enhancing the durability of modern cement-based materials such as ultra-high performance concrete (UHPC) in real environmental conditions. Leveraging the rapid and stable equilibrium attainment of microscopic tests in terms of RH and T, this study investigates, for the first time, the micro-scale splitting tensile strength of cement paste incorporating fine limestone filler (LF) at different RH (10, 30, and 80 %) and T (20, 40, and 60°C). First, micrometer-sized cubes (150 × 150 × 150 µm 3 ) were fabricated using cement paste with a constant w/c ratio of 0.40, while substituting cement with LF at 15 % and 30 %, resulting in water-to-fine ratios of 0.40, 0.34 and 0.28. Then, micro-cubes were tested with a nano-indenter equipped with an environmental chamber able to apply varying RH and T conditions. Additionally, X-ray computed microtomography (µ-CT) and mercury intrusion porosimetry (MIP) were used to characterize porosity and pore-network connectivity. The results show that LF reduces porosity and refines pore structure, improving tensile strength but only partially mitigating strength loss at higher RH and T levels. A quadratic model describes the non-linear correlation between strength, RH, and T. Coupled hygro-thermal effects indicate that higher RH slightly offsets thermal weakening in cement paste but has a reduced influence in systems with LF. Finally, the micro-scale splitting test effectively assesses hygro-thermal effects on cement paste fracture performance, providing valuable insights into UHPC durability. • Micro-scale splitting test assessed the fracture of cement paste with limestone. • At low w/f ratios, limestone enhances micro-scale splitting tensile strength. • Limestone reduces porosity and connectivity, while refining the pore structure. • Higher RH and T reduce splitting strength, while limestone slightly mitigates it. • Pore-network connectivity governs the moisture-induced weakening on cement paste.
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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 | 0.001 |
| 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".