Use of Crab Shell (Ucides cordatus) in Portland Cement Matrices
Bibliographic record
Abstract
The high consume of crustaceans in human food has generated a large quantities of residues, such as the crab shell of Ucides cordatus (caranguejo-uçá), in Brazil. These residues are disposed in the environment. The development of new materials using crab shells chitin for biotechnological applications in civil construction is of great interest to the scientific community. The residues addition in the cement can reduce electricity consumption, CO2 emissions and other environmental damage from this human activity. Thus, the aims of this study were the use of U. Cordatus residues for hydroxyapatite and chitosan production and the incorporation of these compounds in Portland cement matrix, as a viable alternative to improve the properties of the paste and mortar when fresh or hardened. The crab shells were obtained from a fishermen's cooperative after meat extraction. The cement for the production of pastes and mortars was CPII F-40 Portland with filer. The proportion of biomaterial in the cement matrix was of 1 to 5% (w/w). The physical and chemical properties of this material were determined in the fresh and hardened states. Biopolimers of the crab shells promoted changes in consistency, reduced setting time of pastes and mortars and an increase in strength to the axial compressive. These changes may be due to the hydrophilic groups of this compound and the greatest water retention that causes increase the number of nucleation points of the cement and paste grains becomes denser and homogeneous. Thus, the addition of biopolimers in the cement matrix may function as a polyfunctional additive. Furthermore, this process contributes to the reduction of environmental damage caused by improper disposal of crab shells and may represent an economic enhancement of this by-product of the food industry.
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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) | 0.001 | 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".