Nguyễn et al. (2026) — Ambient-Cured One-Part Engineered Geopolymer Composites with 20.9 % Ductility

Citation

Phương Hoàng Nguyễn, Huy Hoàng Nguyễn, Quang-Hiếu Lương, Youngsang Kim, Bang Yeon Lee (2026). Ambient Temperature Curing Stimulated One-Part Engineered Geopolymer Composites with Extremely High Ductility and Low Thermal Conductivity. Journal of Materials in Civil Engineering, 38(4), 04026063.

• DOI: 10.1061/JMCEE7.MTENG-22099
• Atlas layer: extension
• Related Victor Li book chapter: Chapter 9: Green ECC & Chapter 4: Micromechanics-Based Material Design
• Source PDF: primary_data/nguyen-2026-ambient-temperature-curing-stimulated-one-part.pdfIJP08826E_Ambient temperature EGC_ASCE.pdf`
• Extracted text: secondary_data/full_texts/nguyen-2026-ambient-temperature-curing-stimulated-one-part_full_text.mdsecondary_data/full_texts/IJP08826E_Ambient temperature EGC_ASCE_full_text.md`
• Source note: secondary_data/source_notes/nguyen-2026-ambient-temperature-curing-stimulated-one-part_source_note.mdsecondary_data/source_notes/IJP08826E_Ambient temperature EGC_ASCE_source_note.md`

Why this paper matters

Eliminates the critical high-temperature curing barrier of geopolymer composites by formulating an ambient-temperature-cured one-part system (OP-EGC: 72 % fly ash, 18 % slag, 10 % solid anhydrous sodium metasilicate, 1.2 vol. % PE fibers). Proves that incorporating 1–2 mm expanded polystyrene (EPS) beads (OP-EGC-A-SE) introduces engineered artificial flaws that lower first cracking strength ($1.47\text{ MPa}$), achieving an extraordinary direct tensile strain capacity of $20.90 \pm 1.28\text{ \%}$ (surpassing rebar extensibility), coupled with a low thermal conductivity of $0.58\text{ W/m}\cdot\text{K}$ (4x lower than normal concrete) and high impact resistance surviving 61 drop-weight cycles on steel.

Main contribution

• Record 20.90 % Ductility in Ambient-Cured One-Part EGC: OP-EGC-A-SE achieved $20.90 \pm 1.28\text{ \%}$ direct tensile strain capacity with 92.8 microcracks ($l_s = 0.86\text{ mm}, w_c = 180.1\ \mu\text{m}$) without any thermal curing.
• Multifunctional Thermal Insulation: Achieved a low thermal conductivity of $0.58\text{ W/m}\cdot\text{K}$ ($\rho_h = 1.70\text{ g/cm}^3$), delivering 4x better thermal isolation than standard concrete ($2.24\text{ W/m}\cdot\text{K}$).
• High Impact Energy Dissipation: 10 mm overlay on a steel beam survived 61 successive drop-weight impact cycles without shattering or delaminating.
• Mineralogical Co-Existence of Gels: Confirmed the formation of both calcium-rich C-(N)-A-S-H gel and aluminosilicate N-A-S-H gel.

Evidence summary

• Density & Compressive Strength:
• OP-EGC-A (No EPS, Air): $f_c = 24.5\text{ MPa}$, $\rho_h = 1.86\text{ g/cm}^3$ (Fig. 7, Page 5).
• OP-EGC-W (No EPS, Water): $f_c = 21.6\text{ MPa}$, $\rho_h = 1.80\text{ g/cm}^3$.
• OP-EGC-A-SE (1–2 mm EPS): $f_c = \mathbf{13.9\text{ MPa}}$, $\rho_h = \mathbf{1.70\text{ g/cm}^3}$.
• OP-EGC-A-ME (4–5 mm EPS): $f_c = 10.2\text{ MPa}$, $\rho_h = 1.63\text{ g/cm}^3$.
• Direct Uniaxial Tensile Properties:
• OP-EGC-A-SE: $\sigma_{1c} = 1.47 \pm 0.18\text{ MPa}$, $\sigma_{tu} = 2.52 \pm 0.16\text{ MPa}$, $\epsilon_{ts} = \mathbf{20.90 \pm 1.28\text{ \%}}$, $f_{ts}/f_c = 18.1\text{ \%}$, 92.8 cracks ($l_s = 0.86\text{ mm}, w_c = 180.1\ \mu\text{m}$) (Table 4 & Figs. 8–9, Pages 6–7).
• OP-EGC-A: $\sigma_{1c} = 3.81\text{ MPa}$, $\sigma_{tu} = 5.21\text{ MPa}$, $\epsilon_{ts} = 15.66 \pm 0.10\text{ \%}$, 84.1 cracks.
• OP-EGC-A-ME: $\sigma_{1c} = 1.48\text{ MPa}$, $\sigma_{tu} = 2.50\text{ MPa}$, $\epsilon_{ts} = 14.24 \pm 0.90\text{ \%}$.
• OP-EGC-W: $\sigma_{1c} = 2.63\text{ MPa}$, $\sigma_{tu} = 4.85\text{ MPa}$, $\epsilon_{ts} = 6.75 \pm 0.70\text{ \%}$.
• Thermal Conductivity & Impact Resistance:
• OP-EGC-A-SE thermal conductivity: $0.58\text{ W/m}\cdot\text{K}$ vs $2.24\text{ W/m}\cdot\text{K}$ for normal concrete (Fig. 11 & Table 6, Page 7).
• Impact survival: 61 drops for OP-EGC-A-SE vs 1 drop for unreinforced paste (Fig. 13, Page 8).
• Microstructure: Loose ITZ gap grooves around EPS beads confirmed via SEM (Fig. 15, Page 8); EDS ternary diagram confirmed C-(N)-A-S-H and N-A-S-H gels (Fig. 16, Page 8).

Linked Atlas nodes

• 04_material_systems/cementless_composites.md
• 04_material_systems/green_ecc.md
• 02_concepts/flaw_design.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 9 (Green ECC) and Chapter 4 (Micromechanics) by eliminating heat curing through a solid-activator one-part geopolymer design, and demonstrating that artificial flaw tailoring via 1–2 mm EPS beads unlocks an extraordinary $20.90\text{ \%}$ direct tensile strain capacity, coupled with $0.58\text{ W/m}\cdot\text{K}$ thermal insulation and 61-cycle impact resistance.

Claim-evidence rows to add

Verification status

• PDF preserved: yes (in primary_data/IJP08826E_Ambient temperature EGC_ASCE.pdf)
• Text extracted: yes (PyMuPDF, 10 pages)
• DOI verified: yes (10.1061/JMCEE7.MTENG-22099)
• Page/figure/table verified: yes (all checked in PDF text)
• Claim-evidence matrix ready: yes

Cautions

• Compressive strength of OP-EGC-A-SE is $13.9\text{ MPa}$, best suited for lightweight facades and energy-absorbing structural overlays.
• Water immersion during curing induces alkali leaching, reducing tensile ductility.