Cementitious Liners in Reinforced Concrete Pipes
Bibliographic record
Abstract
This thesis investigates the performance of damaged reinforced concrete pipes with a focus on developing design approaches to examine the required thickness of cementitious liners to restore strength to resist earth and vehicle loads. Design seeks to prevent the development of additional cracking within the damaged concrete pipe and cracking within the liner material due to circumferential bending moments at the pipe crown, to limit both stormwater contact with reinforcing and continued pipe corrosion. Several different deteriorated pipe conditions are considered: flexural cracks, losses of concrete cover and tensile reinforcement, as well as an extreme condition where the host pipe is assumed to have lost all capacity to resist bending moments. Sample calculations quantify how the required cementitious liner thickness increases as the extent of deterioration within the concrete pipe increases. The project involves both theoretical and experimental work. An experimental program was undertaken to examine the mechanics of cracked reinforced concrete pipes. The experimental work presented in this thesis serves as a first step in forming an understanding between the developed cracks and bending moments within reinforced concrete pipes (where bending moments influence both reinforced concrete pipe design as well as cementitious liner design). Reinforced concrete pipes were instrumented with optical fibres and then buried in graded granular fill. Strain measurements around the inner and outer surfaces were taken as burial depth was increased from 0.6m to 1.2m. The measured strains showed the continuous evolution of crack widths as curvatures associated with bending moments increased with burial. Measurements indicated that a 60cm increase in soil cover (approximately 1/10th of the standard burial depth for the Class 4 pipes used for experimentation) resulted in increases of crack width between 0.025mm and 0.06mm (approximately 1/10th and 1/5th of the AASHTO allowable crack limit, respectively). The calculated crack widths suggest that reinforced concrete pipe design theory for crack widths is reflected reasonably well.
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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".