Nguyen et al. (2021) — Ultra-ductile behavior of fly ash-based engineered...

Citation

Huy Hoang Nguyen, Quang-Hieu Luong, Jeong-Il Choi, Ravi Ranade, Victor C. Li, Bang Yeon Lee (2021). Ultra-ductile behavior of fly ash-based engineered geopolymer composites with a tensile strain capacity up to 13.7%. Cement and Concrete Composites, Vol. 122, Article 104133.

DOI: 10.1016/j.cemconcomp.2021.104133
Atlas layer: extension
Related Victor Li book chapter: Chapter 4: Non-Portland / Geopolymer ECC; Chapter 5: Advanced ECC
Source PDF: nguyen-2021-ultra-ductile-behavior-of-fly-ash-based.pdf
Extracted text: atlas/full_text/nguyen-2021-ultra-ductile-behavior-of-fly-ash-based_full_text.md
Source note: atlas/source_notes/nguyen-2021-ultra-ductile-behavior-of-fly-ash-based_source_note.md

Why this paper matters

Landmark sustainable geopolymer ECC paper co-authored by Victor Li, developing 100% cement-free fly ash-based UD-EGC achieving a world-record tensile strain capacity of 13.68 ± 0.85% (up to 13.7%) with 1.75 vol% PE fibers, paired with lightweight density ($<1.83\text{ g/cm}^3$) and exceptional tensile-to-compressive strength ratios (35–45%).

Main contribution

Formulated 100% fly ash-based geopolymer ECC using sodium metasilicate pentahydrate (SMP) dissolved in 7.2 M NaOH solution.
Achieved world-record tensile strain capacity in geopolymer ECC ($\varepsilon_{tu} = 13.68\%$, $\sigma_{tu} = 6.79\text{ MPa}$, $f_c = 19.3\text{ MPa}$, $\rho = 1.66\text{ g/cm}^3$ in UD-EGC15).
Verified micromechanical mechanism: ultra-low matrix fracture toughness ($K_m = 0.07\text{ MPa}\cdot\text{m}^{1/2}$, $J_{tip} = 0.57\text{ J/m}^2$) combined with moderate fiber friction ($\tau_0 = 0.55\text{ MPa}$) provides huge PSH energy margin.

Evidence summary

Compressive strength & density: $f_c = 15.7\text{--}22.4\text{ MPa}$, $\rho_h = 1.44\text{--}1.83\text{ g/cm}^3$ (meets ACI 318 structural lightweight criteria).
Direct tensile properties:
UD-EGC15: $\sigma_{tc} = 3.70\text{ MPa}$, $\sigma_{tu} = 6.79 \pm 0.58\text{ MPa}$, $\varepsilon_{tu} = 13.68 \pm 0.85\%$ (max 13.7%), $E_t = 0.71\text{ MPa}\cdot\text{m/m}$, $f_{ts}/f_c = 35.1\%$.
UD-EGC20: $\sigma_{tc} = 4.63\text{ MPa}$, $\sigma_{tu} = 8.10 \pm 0.42\text{ MPa}$, $\varepsilon_{tu} = 12.26 \pm 0.71\%$, $E_t = 0.78\text{ MPa}\cdot\text{m/m}$, $f_c = 22.4\text{ MPa}$.
All 4 mixes exceeded 10% tensile ductility (Table 4, page 6).
Crack characteristics: 77.5 microcracks in 80 mm gage length, spacing 1.00 mm, average width 136.7 $\mu\text{m}$.
Micromechanical parameters: $K_m = 0.07\text{ MPa}\cdot\text{m}^{1/2}$, $J_{tip} = 0.57\text{ J/m}^2$, $\tau_0 = 0.55\text{ MPa}$.

Linked Atlas nodes

04_material_systems/geopolymer_ecc.md
02_concepts/extreme_ductility_ecc.md
02_concepts/strain_hardening_criteria.md
05_experiments/direct_tensile_test.md

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/geopolymer_ecc.md`	Fly ash-based engineered geopolymer composite (UD-EGC15) achieves tensile strain capacity up to 13.7% and tensile strength of 6.79 MPa with 1.75 vol% PE fibers.	JSCE uniaxial tensile testing verified average ultimate strain of 13.68 ± 0.85% across specimens.	Pages 1, 5-6, Section 3.2, Table 4, Fig. 6	verified_from_pdf
`02_concepts/strain_hardening_criteria.md`	Ultra-high ductility in UD-EGC is driven by an extremely low matrix fracture toughness (Km = 0.07 MPa·m^(1/2), Jtip = 0.57 J/m^2) and moderate PE interfacial friction (0.55 MPa).	Notched beam fracture and single PE fiber pullout testing confirmed PSH energy criteria satisfaction.	Pages 7-8, Section 3.3, Table 7, Eq. (3)	verified_from_pdf

Verification status

PDF preserved: yes (nguyen-2021-ultra-ductile-behavior-of-fly-ash-based.pdf)
Text extracted: yes (atlas/full_text/nguyen-2021-ultra-ductile-behavior-of-fly-ash-based_full_text.md)
DOI verified: yes (10.1016/j.cemconcomp.2021.104133)
Page/figure/table verified: yes
Claim-evidence matrix ready: yes

Cautions

Requires heat curing at 80 °C for 36 hours.
Average crack widths ($131\text{--}148\ \mu\text{m}$) are larger than PVA-ECC due to lower fiber-matrix interfacial bond.