The Ministry of Transportation of Ontario’S Experience with Electrochemical Chloride Extraction (ECE) 1989-2002
Bibliographic record
Abstract
Abstract The corrosion of steel reinforcement in concrete highway structures involves electrochemical reactions and as such can be arrested by electrochemical means such as cathodic protection or electrochemical chloride extraction (ECE). The ECE method is typically similar to cathodic protection in that it involves application of current. It requires the installation of a temporary anode (5 - 8 weeks) on the surface of the concrete and the passage of direct current between the anode and the steel reinforcement which serves as the cathode. The current density of the ECE process is approximately 100 times the current density used in conventional cathodic protection. The Ministry of Transportation of Ontario (MTO) first used ECE on an experimental basis in 1989. More recently, the Ministry has specified ECE on conventional contractor-bid contracts to mitigate the effect of corrosion distress on 5 piers and 1 abutment at the Burlington Bay Skyway in Burlington and 12 bridge abutments in North Bay, Ontario. Evaluation of ECE by the Ministry has indicated variable performance. Performance as expected, meeting the −250 mV static potential criterion specified by the Ministry has been documented on some structures but not on others. The reason for this variable performance is not yet well understood. The paper will review variables such as total ampere hours passed, depth of concrete cover, depth of chloride corrosion threshold relative to the reinforcement, steel current density compared to concrete current density and corrosion potentials prior to and after treatment. Rate of corrosion measurements by the linear polarization technique will also be presented as well as concrete resistivity readings prior to and after treatment. The paper will attempt to identify parameters that predict the probability of success of the ECE treatment. Typical costs experienced on the Ministry’s ECE contracts to date will also be reported.
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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 | 0.003 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.002 |
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".