Recycling Waste Gypsum Drywalls as Partial Cement Replacement in Concrete Exposed to Different Environmental Conditions
Bibliographic record
Abstract
Recycled gypsum powder from waste drywalls is a new alternative that has been recently introduced for partial cement replacement in concrete for construction applications. It has been shown that the recycled gypsum, alongside fly ash, can partially replace cement in concrete to some extent without hurting the required properties of concrete. In this paper, the impact of recycled gypsum content on the durability of concrete (hereafter called gypsum concrete) exposed to different environmental exposures is evaluated. A total of 153 concrete cylinders (100×200 mm) with different recycled gypsum contents (0%, 10%, and 20% of cement replacement) were considered. Each mix was exposed to air-dry, freshwater, seawater, freshwater–air dry cyclic, and seawater–air dry cyclic conditions. The specimens were tested in compression loading after 1,000, 3,000, and 6,000 h of exposure. Recycled gypsum used in this research was in two types of a powder with fine particles only (hereafter called fine gypsum) and in the form of mixed fine, coarse, and paper particles (hereafter called whole gypsum). Other mechanical and physical properties of concrete such as absorption, volume change, and ultrasonic pulse velocity were analyzed. It was observed that the compressive strength of the specimens with 10% and 20% fine gypsum content at Day 28 was about 36% and 40% lower than that of the control specimens, respectively. However, the strength gap was reduced to about 16% and 7% at the end of 6,000 h in the air-dry condition. The specimens submerged in freshwater and seawater showed a rate of strength gain higher than that of the control specimens, bringing the compressive strength of the gypsum concrete specimens slightly higher than that of the control specimens after 6,000 h exposure. Overall, recycled gypsum in combination with fly ash not only does not hurt the long-term strength of concrete but also can enhance the strength under certain conditions, mostly those exposures involving water exposure.
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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) | 0.001 | 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".