Feng et al. (2024) — Effect of Mix Proportion Parameters on Chloride Erosion Resistance of Fly Ash/Slag-Based Engineered Geopolymer Composites

Citation

Feng, H., Xin, X., Guo, A., Yu, Z., Shao, Q., Sheikh, M. N., & Sun, Z. (2024). Effect of mix proportion parameters on chloride erosion resistance of fly ash/slag-based engineered geopolymer composites. Journal of Cleaner Production, 438, 140785.

DOI: 10.1016/j.jclepro.2024.140785
Atlas layer: extension
Related Victor Li book chapter: Chapter 9: Green ECC (Engineered Geopolymer Composites) & Chapter 10: Long-Term Durability (Chloride Ingress and Diffusion)
Source PDF: feng-2024-effect-of-mix-proportion-parameters.pdf
Extracted text: full_text/feng-2024-effect-of-mix-proportion-parameters_full_text.md
Source note: source_notes/feng-2024-effect-of-mix-proportion-parameters_source_note.md

Why this paper matters

Systematically demonstrates that fly ash/slag-based engineered geopolymer composites (EGC) reinforced with PE fibers deliver exceptional chloride erosion resistance ($D_{app} = 0.0661 \times 10^{-12}\text{ m}^2/\text{s}$), high compressive strength (70–80 MPa), and extreme direct tensile ductility (up to 8.0 %), providing a comprehensive parametric map across slag content, $w/b$, activator dosage, and fiber volume.

Main contribution

Synthesizes ambient-cured FA/GGBS-EGC using anhydrous sodium metasilicate powder and PE fibers ($l_f = 12\text{ mm}$, $d_f = 24\ \mu\text{m}$, $\sigma_f = 3000\text{ MPa}$).
Quantifies four parametric effects (slag ratio 40–100 %, $w/b = 0.32\text{--}0.38$, activator 4–6 %, fiber $V_f = 1.0\text{--}2.0\%$) on both mechanical ductility and chloride diffusion.
Discovers that increasing slag content (from 40 % to 100 %) and activator dosage enhances C-(A)-S-H gel formation and chemical/physical chloride binding, lowering chloride diffusion coefficient by more than 80 %.
Achieves an optimal multi-property envelope: compressive strength $f_c = 70\text{--}80\text{ MPa}$, ultimate tensile strength $\sigma_u = 5.0\text{--}6.2\text{ MPa}$, tensile strain capacity $\epsilon_u$ up to 8.0 %, and chloride diffusion coefficient $D_{app} = 0.0661 \times 10^{-12}\text{ m}^2/\text{s}$.

Evidence summary

Precursors & Activator: Fly Ash (Class F, $54.0\%\ \text{SiO}_2, 31.2\%\ \text{Al}_2\text{O}_3$) + GGBS ($35.3\%\ \text{CaO}, 32.2\%\ \text{SiO}_2$), activated with solid anhydrous $\text{Na}_2\text{SiO}_3$ (4–6 wt%).
PE Fiber Specifications: Length $l_f = 12\text{ mm}$, diameter $d_f = 24\ \mu\text{m}$, tensile strength $\sigma_f = 3000\text{ MPa}$, elastic modulus $E_f = 100\text{ GPa}$, density $0.97\text{ g/cm}^3$, volume fraction $V_f = 1.0\%\text{ to }2.0\%$.
Mechanical Properties (28-day curing):
Compressive strength: 70.2 to 82.5 MPa.
Direct tensile strength: 5.12 to 6.20 MPa.
Direct uniaxial tensile strain capacity: $5.5\%\text{ to }8.0\%$.
Chloride Transport Properties:
Diffusion coefficient ($D_{app}$): $0.0661 \times 10^{-12}\text{ m}^2/\text{s}$ (1–2 orders of magnitude lower than OPC concrete).
Microstructural analysis: Slag densifies C-A-S-H gel matrix and refines pore structure, while PE fiber bridging prevents microcrack propagation during exposure.

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/chloride_diffusion_test.md
05_experiments/direct_tensile_test.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 9 (Green ECC) and Chapter 10 (Long-Term Durability).
Demonstrates that high-slag EGC not only satisfies pseudo strain-hardening criteria with extreme ductility ($\epsilon_u \approx 8\%$), but also surpasses Portland cement ECC in chloride durability due to superior chemical binding in aluminosilicate C-(A)-S-H gels.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/geopolymer_ecc.md`	Fly ash/slag-based EGC achieves direct tensile ductility up to 8 % and compressive strength of 70–80 MPa	Uniaxial tensile testing on dogbone specimens showed $\epsilon_u = 8.0\%$ with $\sigma_u = 5.8\text{ MPa}$ and $f_c = 78.5\text{ MPa}$	Section 3.1 & 3.2, Fig. 4-6, Table 4	verified_from_pdf
`05_experiments/chloride_diffusion_test.md`	Increasing slag content to 100 % in EGC reduces apparent chloride diffusion coefficient to $0.0661 \times 10^{-12}\text{ m}^2/\text{s}$	Chloride immersion testing and titration profiling quantified diffusion coefficients across varying slag ratios	Section 3.3 & 3.4, Fig. 8-11, Table 5	verified_from_pdf
`04_material_systems/pe_ecc.md`	Polyethylene fibers inhibit microcrack opening during chloride exposure, preventing accelerated chloride transport	Microstructural SEM and XRD analysis confirmed C-A-S-H phase stability and fiber bridging integrity	Section 4, Fig. 13-16	verified_from_pdf

Verification status

PDF preserved: yes (feng-2024-effect-of-mix-proportion-parameters.pdf)
Text extracted: yes (full_text/feng-2024-effect-of-mix-proportion-parameters_full_text.md)
DOI verified: yes (10.1016/j.jclepro.2024.140785)
Metadata verified: yes (Journal of Cleaner Production, Vol. 438, 140785, 2024)
Claim-evidence matrix ready: yes

Cautions

High slag content (> 80 %) reduces setting time; superplasticizer and retarder dosages must be optimized for castability.
Chloride testing was conducted on uncracked and pre-cracked coupons in laboratory NaCl immersion; long-term tidal exposure data is pending.