Corrosion Studies on Reinforced Concrete Produced with Secondary Treated Wastewater and Fly Ash with Sodium Nitrite as Corrosion Inhibitor
Bibliographic record
Abstract
This study investigates the feasibility of utilizing secondary treated wastewater (STW) as a sustainable alternative to potable water for concrete production, focusing on its impact on steel reinforcement corrosion.Concrete samples of M30 grade were prepared with 10% fly ash as a partial cement replacement and varying sodium nitrite concentrations (1%, 2%, and 3% by weight of cement) as corrosion inhibitors.The corrosion activity was assessed over a 420-day period using the half-cell potentiometer test, a standardized nondestructive method (ASTM C876-15).The study analyzed corrosion potentials at two concrete cover depths (50 mm and 100 mm) across samples prepared with STW from three treatment plants in Bangalore: Bellandur, Jakkur, and Nagasandra.Results showed that sodium nitrite effectively reduced corrosion risk, particularly at 1% and 2%, where corrosion potentials remained above -200 mV after 420 days, indicating less than a 10% probability of corrosion.A 100 mm cover depth provided better corrosion protection compared to 50 mm, emphasizing the importance of sufficient cover.STW samples with higher residual chlorides and dissolved solids showed initial susceptibility, but the combination of fly ash and sodium nitrite mitigated corrosion effectively.By the end of 420 days, the treated samples demonstrated corrosion performance comparable to potable water.This study confirms that with proper modifications, STW can be a viable alternative in concrete mixing, contributing to sustainable construction practices while maintaining structural integrity and durability over extended periods.
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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 | 0.001 |
| 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 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".