Nguyen et al. (2026) — Hybrid PE-PBO Fiber Reinforced Lightweight Engineered Geopolymer Composites

Citation

Phuong Hoang Nguyen, Huy Hoang Nguyen, Quang-Hiếu Lương, Se-Eon Park, Hyeongki Kim, Bang Yeon Lee (2026). Combined effect of hybrid PE-PBO fiber reinforcement on the mechanical properties of lightweight fly ash-slag-based engineered geopolymer composites at ambient temperature and after exposure to elevated temperatures. Developments in the Built Environment, 26, 100938.

• DOI: 10.1016/j.dibe.2026.100938
• Atlas layer: extension
• Related Victor Li book chapter: Chapter 9: Green ECC & Chapter 4: Micromechanics-Based Material Design
• Source PDF: primary_data/nguyen-2026-combined-effect-of-hybrid-pe-pbo.pdfIJP08926E_Combined effect of PE-PBO_DIBE.pdf`
• Extracted text: secondary_data/full_texts/nguyen-2026-combined-effect-of-hybrid-pe-pbo_full_text.mdsecondary_data/full_texts/IJP08926E_Combined effect of PE-PBO_DIBE_full_text.md`
• Source note: secondary_data/source_notes/nguyen-2026-combined-effect-of-hybrid-pe-pbo_source_note.mdsecondary_data/source_notes/IJP08926E_Combined effect of PE-PBO_DIBE_source_note.md`

Why this paper matters

Resolves the trade-off between the high ductility of PE fibers (melting at 150 °C) and the high thermal stability of PBO fibers (typically limited to $<1.5\text{ \%}$ strain capacity) by hybridizing PE and PBO fibers at an ultra-low total dosage of $1.0\text{ vol. \%}$ (0.5 % PE + 0.5 % PBO) in an EPS-modified lightweight geopolymer matrix ($\rho_h = 1.50\text{ g/cm}^3, f_c = 20.9\text{ MPa}$). Achieves an ambient direct tensile strain capacity of $4.14 \pm 0.17\text{ \%}$ with tight crack widths of $51.1\ \mu\text{m}$, while enabling mono-PBO EGC to reach $3.01\text{ \%}$ (2x literature baseline) and preserving strain-hardening up to 200 °C after early-age heating.

Main contribution

• Low-Dosage PE-PBO Hybridization: Demonstrated that 0.5 % PE + 0.5 % PBO achieves balanced performance: $\sigma_{cr} = 3.79\text{ MPa}, \sigma_{tu} = 5.17\text{ MPa}$, $\epsilon_{ts} = 4.14 \pm 0.17\text{ \%}$, and $w_c = 51.1\ \mu\text{m}$.
• Unlocking PBO Ductility via EPS Flaw Tailoring: Mono-PBO composite (EGC-BO) reached $\epsilon_{ts} = 3.01 \pm 0.15\text{ \%}$ and $w_c = 36.1\ \mu\text{m}$, double previous PBO composite records, by using 1–2 mm EPS beads to lower matrix fracture toughness.
• Elevated Temperature Resilience (100–300 °C):
• At 100 °C, early-age heating boosted ductility to $5.34\text{ \%}$ (EGC-EBO) and $3.58\text{ \%}$ (EGC-BO) due to accelerated geopolymerization and enhanced fiber anchoring.
• At 200 °C, EGC-EBO maintained strain-hardening ($\sigma_{tu} = 2.11\text{ MPa}, \epsilon_{ts} = 0.77\text{ \%}$), whereas mono-PE completely lost bridging capability ($\epsilon_{ts} = 0.03\text{ \%}$).
• At 300 °C, PBO fibers prevented catastrophic brittle collapse, preserving residual load capacity ($\sigma_{tu} = 1.60\text{--}2.73\text{ MPa}$).

Evidence summary

• Ambient Properties:
• EGC-E (R) (1.0 % PE): $\rho_h = 1.45\text{ g/cm}^3, f_c = 20.7\text{ MPa}, \sigma_{tu} = 4.92\text{ MPa}$, $\epsilon_{ts} = \mathbf{12.76 \pm 0.26\text{ \%}}$, $w_c = 116.8\ \mu\text{m}$ (Tables 4, 5, 8 & Fig. 6a, Pages 4, 6, 9, 11).
• EGC-BO (R) (1.0 % PBO): $\rho_h = 1.54\text{ g/cm}^3, f_c = 19.6\text{ MPa}, \sigma_{tu} = 5.79\text{ MPa}$, $\epsilon_{ts} = \mathbf{3.01 \pm 0.15\text{ \%}}$, $w_c = \mathbf{36.1\ \mu\text{m}}$.
• EGC-EBO (R) (0.5 % PE + 0.5 % PBO): $\rho_h = 1.50\text{ g/cm}^3, f_c = 20.9\text{ MPa}, \sigma_{tu} = 5.17\text{ MPa}$, $\epsilon_{ts} = \mathbf{4.14 \pm 0.17\text{ \%}}$, $w_c = \mathbf{51.1\ \mu\text{m}}$.
• Early-Age Heating Performance (4 Days):
• 100 °C: EGC-EBO-100 (E) $\epsilon_{ts} = \mathbf{5.34\text{ \%}}$, EGC-BO-100 (E) $\epsilon_{ts} = \mathbf{3.58\text{ \%}}$ (Table 6, Page 9).
• 200 °C: EGC-EBO-200 (E) $\sigma_{tu} = 2.11\text{ MPa}, \epsilon_{ts} = \mathbf{0.77\text{ \%}}$ vs EGC-E-200 (E) $\epsilon_{ts} = 0.03\text{ \%}$.
• 300 °C: Residual strength preserved ($\sigma_{tu} = 1.60\text{ MPa}$ for EGC-EBO, $2.73\text{ MPa}$ for EGC-BO).
• Microstructure: SEM showed intact PBO fibers bridging porous voids left by melted EPS beads at 300 °C (Fig. 9, Page 12).

Linked Atlas nodes

• 04_material_systems/cementless_composites.md
• 02_concepts/fiber_hybridization.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 showing that hybridizing low-modulus ductile PE and ultra-high strength thermally stable PBO fibers at $1.0\text{ vol. \%}$ total dosage achieves $4.14\text{ \%}$ ambient ductility, $51.1\ \mu\text{m}$ crack tightness, and residual strain-hardening up to 200 °C.

Claim-evidence rows to add

Verification status

• PDF preserved: yes (in primary_data/IJP08926E_Combined effect of PE-PBO_DIBE.pdf)
• Text extracted: yes (PyMuPDF, 13 pages)
• DOI verified: yes (10.1016/dibe.2026.100938)
• Page/figure/table verified: yes (all checked in PDF text)
• Claim-evidence matrix ready: yes

Cautions

• At 300 °C, the material undergoes strain-softening due to PE and EPS bead decomposition.
• Early-age heating benefits geopolymer maturity, while long-term post-curing heating induces pore pressure microcracking.