Effect of Internal Curing on Freeze–Thaw Durability of Dry-Cast Concrete Segmental Retaining Wall Units and Solid Interlocking Concrete Paving Units
Bibliographic record
Abstract
Dry-cast concrete segmental retaining wall (SRW) units and solid interlocking concrete paving units are governed by ASTM C1372 [Standard Specification for Dry-Cast Segmental Retaining Wall Units, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2011] and ASTM C936/C936M [Standard Specification for Solid Concrete Interlocking Paving Units, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2011], respectively. Resistance to freeze–thaw damage is an important performance criterion for these products. These units are produced on machines using vibration-compacted zero-slump concrete. The combination of low water–cement ratio, well-graded aggregates, and intense compaction results in dense, high-strength units without the entrained air necessary in wet-cast concrete to improve freeze–thaw durability. The high-cement content, low-water–cement ratio and short curing time result in a significant percentage of the cement remaining unhydrated. Internal curing (IC) through the use of pre-soaked lightweight aggregates that act as long-term water reservoirs during the cement hydration process is a proven technology that has been optimized in wet-cast concrete to increase the degree of cement hydration and improve durability. For this study, pre-soaked lightweight aggregates were incorporated into SRW units and concrete pavers in an attempt to increase the degree of cement hydration, thereby increasing the quality of the cement paste and improving the freeze–thaw durability of the units. Internally cured SRW units were subjected to ASTM C1262-10 [Standard Test Method for Evaluating the Freeze–Thaw Durability of Dry-Cast Segmental Retaining Wall Units and Related Concrete Units, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2010] freeze–thaw testing. Internally cured concrete pavers were subjected to ASTM C1645-11 [Standard Test Method for Freeze–Thaw and De-Icing Salt Durability of Solid Concrete Interlocking Paving Units, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2011] and CSA A231.2-06 [“Precast Concrete Pavers,” Canadian Standards Association, Mississauga, Ontario, Canada, 2006] freeze–thaw testing in 3 % saline solution, as well as ASTM C418 [Standard Test Method for Abrasion Resistance of Concrete by Sandblasting, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2005] abrasion-resistance testing. The results demonstrate a definite improvement in durability properties of the pavers when internal curing is utilized. In addition, petrographic and scanning electron microscopy studies of the concrete pavers document a significant increase in the degree of cement hydration and quality of the cement paste that is achieved with internal curing. Results of the freeze–thaw tests on SRW units were not conclusive with regard to the effects of internal curing. The petrographic studies of the SRW units showed non-uniform improvement in the degree of cement hydration.
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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 | 0.000 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".