Lv et al. (2025) — Investigation of Mechanical Properties and Microstructural Evolution of Ternary High-Temperature Resistant Engineered Geopolymer Composite (EGC)

Citation

Lv, L., Gan, Y., Wen, B., Dai, L., Chen, J., Kan, L., & Zhang, Z. (2025). Investigation of mechanical properties and microstructural evolution of ternary high-temperature resistant engineered geopolymer composite (EGC). Construction and Building Materials, 487, 142082.

DOI: 10.1016/j.conbuildmat.2025.142082
Atlas layer: core
Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 7: Alternative Reinforcing Fibers (PE Thermal Degradation) & Chapter 10: High-Temperature Durability (pp. 343–384)
Source PDF: lv-2025-investigation-of-mechanical-properties-and.pdf
Extracted text: full_text/lv-2025-investigation-of-mechanical-properties-and_full_text.md
Source note: source_notes/lv-2025-investigation-of-mechanical-properties-and_source_note.md

Why this paper matters

Provides a comprehensive thermal-mechanical investigation of ternary (GGBS-FA-SF) PE-EGC from 20 °C to 800 °C, demonstrating that hydrothermal activation increases tensile strain capacity to 11.03 % at 80 °C, compressive strength peaks at 68.8 MPa at 150 °C, retains 56.64 MPa at 400 °C, and sustains 21.5 MPa at 800 °C with zero explosive spalling.

Main contribution

Develops a ternary high-temperature resistant EGC synthesized from GGBFS, Class F fly ash, and silica fume with 1.50 vol. % PE fibers.
Conducts comprehensive thermal testing across temperature increments: 20 °C, 80 °C, 150 °C, 400 °C, 600 °C, and 800 °C.
Discovers that moderate heat ($80\text{--}150\ ^\circ\text{C}$) triggers internal hydrothermal autoclaving, maximizing tensile ductility to 11.03 % (at 80 °C) and compressive strength to 68.8 MPa (at 150 °C).
Demonstrates exceptional thermal resilience at 400 °C (residual compressive strength of 56.64 MPa, equal to ambient baseline).
Proves that sacrificial PE fiber melting ($T_m \approx 145\ ^\circ\text{C}$) opens micro-pore decompression channels, completely preventing explosive spalling up to 800 °C and retaining 21.5 MPa residual compressive strength via geopolymer matrix sintering.

Evidence summary

Ternary Precursor Matrix: GGBFS (50 wt%), Fly Ash (35 wt%), Silica Fume (15 wt%) activated with liquid waterglass + $\text{NaOH}$ ($M_s = 1.20$), quartz sand ($S/B = 0.36$), $w/b = 0.35$.
Fiber Specifications: 1.50 vol. % UHMWPE fibers ($l_f = 12\text{ mm}, d_f = 24\ \mu\text{m}, \sigma_f = 3000\text{ MPa}, E_f = 100\text{ GPa}$).
Mechanical Properties vs. Temperature:
$20\ ^\circ\text{C}$ (Ambient): $f_c = 58.4\text{ MPa}$, $\sigma_u = 4.85\text{ MPa}$, $\epsilon_u = 8.12\%$.
$80\ ^\circ\text{C}$: $f_c = 63.2\text{ MPa}$, $\sigma_u = \mathbf{5.53\text{ MPa}}$, $\epsilon_u = \mathbf{11.03\%}$.
$150\ ^\circ\text{C}$: $f_c = \mathbf{68.8\text{ MPa}}$, $\sigma_u = 3.82\text{ MPa}$, $\epsilon_u = 3.25\%$ (fiber softening onset).
$400\ ^\circ\text{C}$: $f_c = \mathbf{56.64\text{ MPa}}$ (fiber vaporized; matrix fully stable).
$600\ ^\circ\text{C}$: $f_c = 34.2\text{ MPa}$.
$800\ ^\circ\text{C}$: $f_c = \mathbf{21.5\text{ MPa}}$ (matrix sintering, zero explosive spalling).
Microstructural & Spectroscopic Findings:
FT-IR tracks Si-O-Al and Si-O-Si vibrational shift and bond restructuring.
SEM confirms vaporized fiber channels relieving internal pore vapor pressure without matrix micro-cracking.

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
04_material_systems/geopolymer_ecc.md
04_material_systems/green_ecc.md
04_material_systems/pe_ecc.md
05_experiments/direct_tensile_test.md
05_experiments/thermal_testing.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 7 (PE Fiber Mechanics), and Chapter 10 (Durability / Fire Resistance).
Decouples high-temperature matrix stability from fiber thermal limits: proves that inorganic geopolymer networks (Si-O-Al) remain thermally intact up to 800 °C while sacrificial polymer fiber melting creates an essential pressure-relief network preventing catastrophic explosive spalling.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/geopolymer_ecc.md`	Ternary PE-EGC achieves peak tensile ductility of 11.03 % at 80 °C and retains 56.64 MPa compressive strength at 400 °C	Direct tensile dogbone and cube compression tests across 20 °C to 800 °C	Section 3.1 & 3.2, Fig. 4-8, Table 3	verified_from_pdf
`05_experiments/thermal_testing.md`	Sacrificial melting of PE fibers creates micro-channels that prevent explosive spalling up to 800 °C with residual $f_c = 21.5\text{ MPa}$	Furnace heating trials, boiling water porosity test, and SEM microstructure	Section 3.3 & 3.4, Fig. 9-14, Table 4	verified_from_pdf

Verification status

PDF preserved: yes (lv-2025-investigation-of-mechanical-properties-and.pdf)
Text extracted: yes (full_text/lv-2025-investigation-of-mechanical-properties-and_full_text.md)
DOI verified: yes (10.1016/j.conbuildmat.2025.142082)
Metadata verified: yes (CBM, Vol. 487, 142082, 2025)
Claim-evidence matrix ready: yes

Cautions

Above 150 °C, PE fibers soften and lose tensile load-bearing capacity; tensile strain-hardening is lost above 200 °C, transitioning to unreinforced matrix compression.
For post-fire tensile ductility retention, inorganic fibers (basalt, carbon, steel) must be hybridized with PE.