Nguyen et al. (2023) — Micromechanical and mineralogy analyses on extremely ductile...

Citation

Huy Hoàng Nguyễn, Quang-Hiếu Lương, Phương Hoàng Nguyễn, Hyeong-Ki Kim, Youngsang Kim, Bang Yeon Lee (2023). Micromechanical and mineralogy analyses on extremely ductile engineered geopolymer composites with different activator pretreatments. Journal of Building Engineering, Vol. 80, Article 108093.

DOI: 10.1016/j.jobe.2023.108093
Atlas layer: breakthrough
Related Victor Li book chapter: Chapter 3: Micro-mechanics; Chapter 4: Special ECCs / Geopolymers
Source PDF: nguyen-2023-micromechanical-and-mineralogy-analyses-on.pdf
Extracted text: atlas/full_text/nguyen-2023-micromechanical-and-mineralogy-analyses-on_full_text.md
Source note: atlas/source_notes/nguyen-2023-micromechanical-and-mineralogy-analyses-on_source_note.md

Why this paper matters

Breakthrough investigation discovering that cooling pretreatment of sodium metasilicate-hydroxide activators creates a porous, low-fracture-toughness geopolymer matrix (Km = 0.06 MPa·m¹/²) that amplifies the energy performance index to PSHE = 817.2, unlocking an unprecedented 18.62 ± 1.59% tensile strain capacity in lightweight (1.47 g/cm³) 100% fly ash-based ED-EGCs with 1.75 vol% PE fibers.

Main contribution

Engineered thermal pretreatment protocols for hybrid SMP + SH alkali activators (warming WP vs cooling CP).
Achieved $18.62 \pm 1.59\%$ tensile ductility with $5.54\text{ MPa}$ tensile strength in ED-EGC-CP, setting a world record for fly ash geopolymers.
Quantified micromechanical parameters via single-crack testing and matrix fracture toughness ($K_m = 0.06\text{ MPa}\cdot\text{m}^{1/2}$, $J_{tip} = 0.62\text{ J/m}^2$), proving $PSH_E = 817.2$.

Evidence summary

Physical & Compressive properties: ED-EGC-CP achieved lightweight density $\rho = 1.47\text{ g/cm}^3$ and compressive strength $f_c = 20.7\text{ MPa}$; ED-EGC-WP achieved $f_c = 31.1\text{ MPa}$ (Table 4, page 5, Fig. 8).
Direct tensile properties:
ED-EGC-CP: $f_{cs} = 3.40\text{ MPa}$, $f_{ts} = 5.54 \pm 0.10\text{ MPa}$, $\varepsilon_{tu} = 18.62 \pm 1.59\%$, $U_t = 0.83\text{ MPa}\cdot\text{m/m}$, 72.8 cracks (Table 4, page 9, Fig. 9b).
ED-EGC-WP: $f_{cs} = 4.67\text{ MPa}$, $f_{ts} = 8.72 \pm 0.76\text{ MPa}$, $\varepsilon_{tu} = 10.97 \pm 1.31\%$, $U_t = 0.73\text{ MPa}\cdot\text{m/m}$, 50.0 cracks (Table 4, Fig. 9a).
Micromechanics: $PSH_E = J_b'/J_{tip} = 817.2$ in ED-EGC-CP (Table 7, page 10).

Linked Atlas nodes

02_concepts/extreme_ductility_ecc.md
04_material_systems/green_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
`02_concepts/extreme_ductility_ecc.md`	Fly ash-based ED-EGC with cooling-pretreated activators achieves an unprecedented tensile strain capacity of 18.62 ± 1.59% and density of 1.47 g/cm³.	JSCE direct tensile testing on dumbbell specimens verified 18.62% tensile strain capacity.	Pages 1, 5, 9, Section 3.1 & Abstract, Tables 4, 5, Figs. 8, 9b	verified_from_pdf
`02_concepts/strain_hardening_criteria.md`	Cooling activator pretreatment lowers matrix fracture toughness to Km = 0.06 MPa·m¹/² and Jtip = 0.62 J/m², amplifying the energy performance index to PSHE = 817.2.	Notched beam fracture toughness and single-crack tension tests verified Km = 0.06 and PSHE = 817.2.	Pages 8, 10, Section 3.2, Tables 6, 7, Eq. 2	verified_from_pdf

Verification status

PDF preserved: yes (nguyen-2023-micromechanical-and-mineralogy-analyses-on.pdf)
Text extracted: yes (atlas/full_text/nguyen-2023-micromechanical-and-mineralogy-analyses-on_full_text.md)
DOI verified: yes (10.1016/j.jobe.2023.108093)
Page/figure/table verified: yes
Claim-evidence matrix ready: yes

Cautions

Compressive strength of the 18.6% ductility mix is moderate (20.7 MPa); high superplasticizer content requires 5 days ambient pre-curing.