Crack Width, Durability, and Self-Healing

1. Learning objectives

• Explain crack width as a durability variable.
• Distinguish visual closure, permeability recovery, and chloride resistance.
• Explain how fiber bridging supports healing.

2. Key concepts

• Crack-width control
• Transport
• Permeability
• Chloride diffusion
• Autogenous healing
• Recovery vs closure

3. Minimal theory

ECC durability follows from distributed tight cracks. Narrow cracks reduce transport and promote healing products, but water-tightness does not always mean chloride resistance.

4. Source-grounded evidence

• Node: 04_material_systems/self_healing_ecc.md.
• Lab card: 06_lab_position/self_healing_position.md.
• Lab evidence matrix: 07_visualization/by_lee_lab_publications_claim_evidence_matrix.csv.

5. Representative papers

• Nguyen 2018/2019 self-healing.
• Choi 2021 fiber hybridization and healing.
• Alemu 2023 permeability.
• Alemu 2025 chloride/corrosion.

6. Figures/tables to show later

• Crack-width histogram.
• Permeability reduction curve.
• Before/after crack images.

7. Discussion questions

1. Why can fiber-reinforced cracks heal differently from mortar cracks?
2. What metric best represents durability recovery?
3. What is the role of SAP/SHA relative to crack width?

8. Assignment idea

Design a self-healing test plan with at least two metrics beyond visual closure.

9. Linked Atlas nodes

• 04_material_systems/self_healing_ecc.md
• 02_concepts/self_healing_mechanisms.md
• 05_experiments/crack_width_distribution.md
• 02_concepts/permeability.md

10. Suggested reading path

1. 04_material_systems/self_healing_ecc.md
2. 06_lab_position/self_healing_position.md

Evidence files

• 07_visualization/foundational_papers_claim_evidence_matrix.csv
• 07_visualization/extreme_ductility_extension_claim_evidence_matrix.csv
• 07_visualization/sustainable_ecc_extension_claim_evidence_matrix.csv
• 07_visualization/by_lee_lab_publications_claim_evidence_matrix.csv