Durability of GFRP Rebars in Simulated Concrete Solutions under Accelerated Aging Conditions
Bibliographic record
Abstract
This paper discusses the potential ingress and effects of simulated concrete pore solution species on glass fiber-reinforced polymer (GFRP) rebars. Knowing that diffusion of moisture into the fiber-matrix interphase in a composite could cause fiber-matrix debonding and that the presence of alkalis at the location of the glass surface would lead to fiber degradation, particular attention was devoted to investigating whether GFRP rebars allow both species to penetrate or allow only water, while blocking the alkalis. To investigate this scenario, GFRP rebars were immersed in five types of simulated concrete pore solutions at elevated temperatures. Penetration of alkalis was assessed using X-ray mapping of backscattered electron images (BEI) and crosschecked by line and point energy dispersive spectroscopy (EDS) techniques. The effects of diffusion at the fiber-matrix interphase were observed by investigating the degradation of constituents at the interphase. Degradation of polymer matrix was assessed by a Fourier transform infrared (FTIR) spectroscopy. Degradation of fiber was investigated by observing highly magnified scanning electron microscopy (SEM) images and point EDS analyses close to the interphase. Debonding of fibers from the matrix was investigated using a SEM technique. Fiber-matrix debonding took place in a few samples, despite the fact that the glass fibers and polymer matrix remained essentially intact and that no penetration of alkalis into the GFRP rebars was observed. This debonding, which occurred only for samples exposed to 75°C, is believed to be caused by hydrolysis of fiber sizing at high temperatures. Finally, this study shows that the vinyl ester (VE) polymer matrix used acts as an effective semipermeable membrane by allowing the penetration of water, while blocking alkali ions.
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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 | 0.001 |
| 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".