Acceleration of the rate of the strength development for concrete mixes containing 30% replacement of portland cement by fly ash
Bibliographic record
Abstract
The merits of the use of fly ash in concrete mixes have been widely published. A replacement of cement > 20%, however, decreases productivity in construction. The use of an accelerating admixture to offset the delayed hydration resulting from the inclusion of fly ash levels >20 % in normal portland cement concrete mixtures is discussed. The objective of this investigation was to produce a concrete mixture with a significant amount (30%) of fly ash and yet developed early strength similar to 100% normal portland cement mixtures. The mechanism of the acceleration process of the fly ash/normal portland cement hydration will be discussed subsequently in a companion paper. Concrete mixtures with design strengths of 35 MPa containing a 30% replacement fly ash were accelerated to achieve 1 day-strength comparable to 100% normal portland cement. Mechanical properties such as compressive strength development were determined. The degree and rate of hydration were followed by X-ray diffraction, thermal analysis, and conduction calorimetry. It is shown that the addition of a new experimental accelerator in fly ash mixtures containing 30% fly ash replacement provided a compressive strength close to that obtained from a 100% normal portland cement mixture. The similarity of the hydrates formed in mortar mixtures containing the accelerator to mixtures containing 100% normal portland cement was also confirmed by X-ray diffraction and thermal analysis.
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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) | 0.002 | 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".