Kan et al. (2025b) — High-Temperature Resistance of Engineered Geopolymer Composite: Isolating the Effects of Key Components

Citation

Kan, L., Lv, L., Chen, H., Wen, B., Ma, X., & Wang, F. (2025). High-temperature resistance of engineered geopolymer composite: Isolating the effects of key components. Construction and Building Materials, 481, 141664.

DOI: 10.1016/j.conbuildmat.2025.141664
Atlas layer: extension
Related Victor Li book chapter: Chapter 8: High-Temperature and Fire Resistance of ECC & Chapter 9: Green ECC (Slag/Fly Ash Systems & Recycled Aggregates)
Source PDF: kan-2025-high-temperature-resistance-of.pdf
Extracted text: full_text/kan-2025-high-temperature-resistance-of_full_text.md
Source note: source_notes/kan-2025-high-temperature-resistance-of_source_note.md

Why this paper matters

Systematically isolates the individual effects of four primary mixture components (GGBS/FA ratio, natural vs. recycled sand, $S/B$ ratio, and $W/B$ ratio) on the high-temperature behavior of PE-EGC from 20 °C to 800 °C, proving that optimizing $S/B = 0.60$ achieves a residual compressive strength of 36.0 MPa after 800 °C exposure via ceramic akermanite sintering.

Main contribution

Isolates the parametric influence of: (1) Slag-to-Fly Ash ratio (20:80, 50:50, 80:20), (2) aggregate type (river sand vs. 100 % construction demolition recycled sand), (3) sand-to-binder ratio ($S/B = 0.30, 0.45, 0.60$), and (4) water-to-binder ratio ($W/B = 0.30, 0.40, 0.50$) on PE-EGC (1.50 vol. % PE fibers).
Tests thermal deterioration across 20 °C, 200 °C, 400 °C, 600 °C, and 800 °C.
Discovers that higher $S/B$ (0.60) dilutes paste shrinkage, increases thermal dimensional stability, and yields a residual compressive strength of 36.0 MPa at 800 °C (+7 % higher at 600 °C than at 20 °C).
Proves that porous recycled sand and higher $W/B$ ratios promote steam vapor dissipation, suppressing explosive thermal spalling.
Identifies ceramic phase transformations via XRD/TG: transformation of amorphous C-A-S-H/N-A-S-H gels into refractory akermanite ($\text{Ca}_2\text{Mg}[\text{Si}_2\text{O}_7]$) and gehlenite crystals at 800 °C.

Evidence summary

Precursors & Activator: GGBS + Fly Ash + 10 wt% Silica Fume activated with liquid $\text{Na}_2\text{SiO}_3 + \text{NaOH}$ ($M_s = 1.3$).
Aggregates: River sand ($d_{50} = 250\ \mu\text{m}$) vs. Recycled sand ($d_{50} = 400\ \mu\text{m}$).
Fiber: 1.50 vol. % UHMWPE fibers ($l_f = 12\text{ mm}, d_f = 24\ \mu\text{m}, \sigma_f = 3000\text{ MPa}, E_f = 100\text{ GPa}$).
Compressive Strength Evolutions after Thermal Exposure:
G5F5 ($S/B = 0.30$): 20 °C = 54.2 MPa; 400 °C = 41.5 MPa; 600 °C = 35.8 MPa; 800 °C = 23.4 MPa.
SB0.60 ($S/B = 0.60$): 20 °C = 48.5 MPa; 400 °C = 46.2 MPa; 600 °C = 51.9 MPa (+7.0 %); 800 °C = 36.0 MPa.
Recycled Sand EGC: Maintained 21.2 MPa at 800 °C with significantly fewer surface thermal microcracks than river sand.
Phase & Microstructural Evolution:
PE fiber melting ($T_m \approx 145\ ^\circ\text{C}$) creates interconnected venting voids, preventing spalling.
High-temperature sintering at 600–800 °C forms crystalline akermanite and gehlenite refractory phases.

Linked Atlas nodes

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

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 8 (High-Temperature Behavior and Fire Resistance, pp. 205–234) and Chapter 9 (Green ECC).
Deepens understanding of fire mechanics in synthetic-fiber cementless composites: shows how fiber burnout voids relieve hydraulic steam pressure, while mineral matrix sintering at $> 600\ ^\circ\text{C}$ creates high-temperature ceramic bonds that preserve structural load-bearing capacity.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`05_experiments/thermal_testing.md`	PE-EGC with $S/B = 0.60$ maintains 36.0 MPa compressive strength after 800 °C exposure via ceramic akermanite sintering	High-temperature furnace testing from 20 °C to 800 °C, cube compression, XRD, and TG	Section 3.2 & 3.4, Fig. 5-7, 10-12	verified_from_pdf
`02_concepts/circular_economy_materials.md`	100 % recycled sand from construction demolition waste enhances vapor pressure release and suppresses thermal cracking in EGC	Comparative thermal crack mapping and mechanical testing of river sand vs recycled sand EGC	Section 3.1 & 3.2, Fig. 4 & 6	verified_from_pdf

Verification status

PDF preserved: yes (kan-2025-high-temperature-resistance-of.pdf)
Text extracted: yes (full_text/kan-2025-high-temperature-resistance-of_full_text.md)
DOI verified: yes (10.1016/j.conbuildmat.2025.141664)
Metadata verified: yes (CBM, Vol. 481, 141664, 2025)
Claim-evidence matrix ready: yes

Cautions

Polyethylene fibers decompose at lower temperatures ($T_m \approx 145\ ^\circ\text{C}$) than PVA fibers ($T_m \approx 230\ ^\circ\text{C}$); tensile strain-hardening is completely lost beyond 200 °C.
High slag contents (> 80 %) in dense matrices with low $S/B$ ratios cause severe thermal surface cracking due to trapped vapor pressure.