EVALUATION OF THE ENVIRONMENTAL, MATERIAL, AND STRUCTURAL PERFORMANCE OF RECYCLED AGGREGATE CONCRETE
Bibliographic record
Abstract
Concrete is the most commonly used building material in the construction industry, and contributes to 52% of construction and demolition waste in Canada.Recycled concrete aggregate (RCA) is one way to reduce this impact.To evaluate the performance of coarse and granular (fine and coarse) RCA in structural concrete applications, four studies were performed: an environmental assessment, a material testing program, a shear performance study, and a flexural performance study.To determine the environmental benefits of recycled aggregate concrete (RAC), three case studies were investigated using different populations and proximities to city centres.Environmental modelling suggested that RCA replacement could result in energy savings and greenhouse gas emission reductions, especially in remote areas.Tests were performed to determine if the volumetric replacement of up to 30% coarse RCA and 20% granular RCA is suitable for structural concrete applications in Canada.Fresh, hardened, and durability properties were evaluated.All five (5) of the RCA mixes showed equivalent material performance to the control mixes and met the requirements for a structural concrete mix.The five (5) RAC mixes were also used in structural testing.One-way reinforced concrete slab specimens were tested to failure to evaluate the shear and flexural performance of the RAC members.Peak capacities of and crack formation within each member were analyzed to evaluate the performance of RAC compared to conventional concrete.The shear capacity of specimens made from four (4) of the five (5) RAC mixtures was higher or equivalent to the control specimens.Specimens of the concrete mixture containing the highest content of recycled aggregate, 20% volumetric replacement of granular RCA, had shear capacities 14.1% lower, and exhibited cracking at lower loads than the control.The average flexural capacities of all RAC specimens were within 3.7% of the control specimens.Results from this research provide evidence that up to 30% coarse recycled concrete aggregate and 10% granular recycled aggregate may be incorporated into structural concrete mixtures without iii altering the behaviour of the structure.Concrete containing 20% volumetric replacement of the natural aggregate with granular RCA should be designed with special consideration of the shear performance.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".