Nguyễn et al. (2019) — Mechanical Properties & Self-Healing of Ultra-Ductile AAS Composites

Citation

Huy Hoàng Nguyễn, Jeong-Il Choi, Hyeong-Ki Kim, Bang Yeon Lee (2019). Mechanical properties and self-healing capacity of eco-friendly ultra-high ductile fiber-reinforced slag-based composites. Composite Structures, 229, 111401.

• DOI: 10.1016/j.compstruct.2019.111401
• Atlas layer: extension
• Related Victor Li book chapter: Chapter 8: Self-Healing and Durability of ECC (also Chapter 4 & Chapter 9)
• Source PDF: primary_data/nguyen-2019-mechanical-properties-and-self-healing-capacity.pdfIJP05019E_Mechanical self healing_COST.pdf`
• Extracted text: secondary_data/full_texts/nguyen-2019-mechanical-properties-and-self-healing-capacity_full_text.mdsecondary_data/full_texts/IJP05019E_Mechanical self healing_COST_full_text.md`
• Source note: secondary_data/source_notes/nguyen-2019-mechanical-properties-and-self-healing-capacity_source_note.mdsecondary_data/source_notes/IJP05019E_Mechanical self healing_COST_source_note.md`

Why this paper matters

Proves that eco-friendly alkali-activated slag composites reinforced with 1.75 vol. % PE fibers achieve an extraordinary direct tensile strain capacity of 8.75 % at 28 days ($\sigma_{tu} = 7.67\text{ MPa}$, $f_c = 42.8\text{ MPa}$) with $\text{Ca(OH)}_2$ activator, alongside 100 % autogenous crack closure for cracks $<30\ \mu\text{m}$ (up to 41 $\mu\text{m}$) and 78.6 % resonant frequency stiffness recovery.

Main contribution

• Record Direct Tensile Strain Capacity (8.75 %): Developed 10 wt. % $\text{Ca(OH)}_2$-activated slag composite (PE-S-Ca) achieving a 28-day tensile strain capacity of $8.75 \pm 0.25\text{ \%}$ with 119.2 micro-cracks (spacing 0.67 mm).
• Complete Autogenous Sealing up to 41 $\mu\text{m}$: Achieved zero residual crack width for cracks $< 30\ \mu\text{m}$ and complete closure for cracks up to $41\ \mu\text{m}$ in PE-S-Ca after 36 days in water.
• Stiffness Recovery & Calcite Crystallization: Recorded 78.6 % resonant frequency recovery ($\text{RF}_{en} = 38.4\text{ \%}$), driven by rhombic calcite ($\text{CaCO}_3$) bridging across crack flanks.

Evidence summary

• Direct Tensile Response at 28 Days:
• PE-S-Ca: $\epsilon_u = 8.75 \pm 0.25\text{ \%}$, $\sigma_{tu} = 7.67 \pm 0.32\text{ MPa}$, $\sigma_{fc} = 3.05\text{ MPa}$, 119.2 cracks ($w_{avg} = 58.4\ \mu\text{m}$, spacing 0.67 mm) (Tables 5 & 7, Pages 5–6).
• PE-S-Na: $\epsilon_u = 8.26 \pm 0.27\text{ \%}$, $\sigma_{tu} = 6.08\text{ MPa}$, $\sigma_{fc} = 2.99\text{ MPa}$, 97.5 cracks ($w_{avg} = 66.5\ \mu\text{m}$, spacing 0.82 mm).
• PE-S-NaS: $\epsilon_u = 6.37 \pm 0.13\text{ \%}$, $\sigma_{tu} = 6.82\text{ MPa}$, $\sigma_{fc} = 3.21\text{ MPa}$, 91.3 cracks ($w_{avg} = 55.4\ \mu\text{m}$, spacing 0.87 mm).
• 28-day Compressive Strength: PE-S-Ca = $42.8\text{ MPa}$, PE-S-Na = $33.2\text{ MPa}$, PE-S-NaS = $45.0\text{ MPa}$ (Table 4, Page 4).
• Self-Healing Closure: Complete closure up to $41\ \mu\text{m}$ (PE-S-Ca) and $33\ \mu\text{m}$ (PE-S-Na) (Figs. 8–11, Pages 7–8).
• Resonant Frequency Recovery: PE-S-Ca reached 78.6 % normalized RF after 36 days (Fig. 12, Page 9).

Linked Atlas nodes

• 04_material_systems/green_ecc.md
• 02_concepts/self_healing_mechanisms.md
• 02_concepts/strain_hardening_criteria.md
• 05_experiments/crack_width_distribution.md
• 05_experiments/direct_tensile_test.md

Relationship to Victor Li book

• Primary book anchor remains Victor Li (2019), Engineered Cementitious Composites (ECC).
• Directly extends Chapter 4, Chapter 8, and Chapter 9 by proving that cementless slag geopolymers can deliver 8.75 % tensile ductility while maintaining excellent autogenous self-healing below $41\ \mu\text{m}$.

Claim-evidence rows to add

Verification status

• PDF preserved: yes (in primary_data/IJP05019E_Mechanical self healing_COST.pdf)
• Text extracted: yes (PyMuPDF, 12 pages)
• DOI verified: yes (10.1016/j.compstruct.2019.111401)
• Page/figure/table verified: yes (all checked in PDF text)
• Claim-evidence matrix ready: yes

Cautions

• Liquid $\text{NaOH}$ activator resulted in lower compressive strength (33.2 MPa) and wider crack widths (66.5 $\mu\text{m}$).