Lin et al. (2023) — Analysis of Stress-Strain Behavior in Engineered Geopolymer Composites Reinforced with Hybrid PE-PP Fibers: A Focus on Cracking Characteristics

Citation

Lin, J.-X., Chen, G., Pan, H.-S., Wang, Y.-C., Guo, Y.-C., & Jiang, Z.-X. (2023). Analysis of stress-strain behavior in engineered geopolymer composites reinforced with hybrid PE-PP fibers: A focus on cracking characteristics. Composite Structures, 323, 117437.

DOI: 10.1016/j.compstruct.2023.117437
Atlas layer: core
Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 7: Alternative Reinforcing Fibers (Hybrid Polymeric Fibers) & Chapter 8: Economic and Sustainability Optimization
Source PDF: lin-2023-analysis-of-stress-strain-behavior-in.pdf
Extracted text: full_text/lin-2023-analysis-of-stress-strain-behavior-in_full_text.md
Source note: source_notes/lin-2023-analysis-of-stress-strain-behavior-in_source_note.md

Why this paper matters

Discovers a synergistic fiber hybridization effect in fly ash/slag EGC: replacing 50 % of expensive UHMWPE fibers with economical PP fibers (1.0 % PE + 1.0 % PP) yields a global peak tensile strain capacity of 9.71 % (68 % higher than 100 % PE-EGC) with only a minor 15 % strength drop, maximizing strain energy per unit cost.

Main contribution

Systematically evaluates five hybrid PE/PP fiber replacement ratios (0 %, 25 %, 50 %, 75 %, 100 % PP at a total 2.0 vol. % dosage) in FA/GGBS geopolymer matrices.
Conducts uniaxial direct tensile testing with microscopic crack evolution tracking and Digital Image Correlation (DIC).
Discovers that a 50:50 hybrid ratio (1.0 vol. % PE + 1.0 vol. % PP) achieves the maximum tensile strain capacity ($\epsilon_u = 9.71\%$) due to staggered slip-pullout kinetics between high-modulus PE and flexible PP filaments.
Formulates and verifies a semi-empirical bilinear tensile constitutive model tailored for hybrid fiber EGC.
Conducts a quantitative economic analysis proving that 50 % PP substitution achieves the highest tensile strain energy per unit cost while cutting total fiber material costs by ~45 %.

Evidence summary

Geopolymer Matrix: Class F Fly Ash + GGBFS activated by liquid $\text{NaOH} + \text{Na}2\text{SiO}_3$ ($M_s = 2.25$), quartz powder ($d_2$ setting retarder.} = 110\ \mu\text{m}, S/B = 0.36$), $\text{BaCl
Fiber Properties ($V_{f,total} = 2.0\text{ vol. \%}$):
UHMWPE: $l_f = 12\text{ mm}, d_f = 24\ \mu\text{m}, \sigma_f = 3000\text{ MPa}, E_f = 100\text{ GPa}$.
PP: $l_f = 12\text{ mm}, d_f = 15\ \mu\text{m}, \sigma_f = 850\text{ MPa}, E_f = 7.5\text{ GPa}$.
Mechanical Performance across Hybrid Ratios:
100 % PE (0 % PP): $\sigma_u = 6.12\text{ MPa}$, $\epsilon_u = 5.78\%$, $w_m = 48\ \mu\text{m}$.
75 % PE / 25 % PP: $\sigma_u = 5.65\text{ MPa}$, $\epsilon_u = 7.42\%$, $w_m = 62\ \mu\text{m}$.
50 % PE / 50 % PP: $\sigma_u = 5.20\text{ MPa}$, $\epsilon_u = \mathbf{9.71\%}$ (+68 % vs. mono-PE), $w_m = 75\ \mu\text{m}$.
25 % PE / 75 % PP: $\sigma_u = 4.15\text{ MPa}$, $\epsilon_u = 4.85\%$, $w_m = 98\ \mu\text{m}$.
100 % PP (0 % PE): $\sigma_u = 2.85\text{ MPa}$, $\epsilon_u = 1.62\%$, $w_m = 165\ \mu\text{m}$.
Crack Characteristics: Saturated multi-cracking is maintained up to 75 % PP substitution; average crack width increases moderately with higher PP ratios.

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
02_concepts/fiber_bridging_law.md
04_material_systems/geopolymer_ecc.md
04_material_systems/pe_ecc.md
04_material_systems/pp_ecc.md
05_experiments/direct_tensile_test.md
02_concepts/circular_economy_materials.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 7 (Alternative Reinforcing Fibers), and Chapter 8 (Life Cycle Cost Optimization).
Validates the synergistic hybridization principle: demonstrates that combining high-strength/high-stiffness PE fibers with compliant PP fibers broadens the crack-bridging displacement window, yielding extreme ductility ($\epsilon_u \approx 10\%$) while dramatically reducing raw material costs.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/pe_ecc.md`	Hybridizing 50 % PP with 50 % PE fibers in EGC elevates direct tensile strain capacity to 9.71 %	JSCE direct uniaxial dogbone tensile tests across 0 % to 100 % PP replacement	Section 3.1 & 3.2, Fig. 4-7, Table 3	verified_from_pdf
`04_material_systems/pp_ecc.md`	50:50 PE/PP hybrid fiber EGC achieves maximum strain energy per unit cost with 45 % fiber cost savings	Quantitative economic modeling and tensile strain energy density integration	Section 3.4 & 4.2, Fig. 10-12, Table 4	verified_from_pdf

Verification status

PDF preserved: yes (lin-2023-analysis-of-stress-strain-behavior-in.pdf)
Text extracted: yes (full_text/lin-2023-analysis-of-stress-strain-behavior-in_full_text.md)
DOI verified: yes (10.1016/j.compstruct.2023.117437)
Metadata verified: yes (Composite Structures, Vol. 323, 117437, 2023)
Claim-evidence matrix ready: yes

Cautions

100 % PP fiber replacement results in loss of saturated multiple cracking ($\epsilon_u$ drops to 1.62 %) and wider crack widths ($> 160\ \mu\text{m}$).
Optimal hybrid ratio is strictly bounded at 50 % PP substitution; ratios $> 75\%$ degrade tensile strength below 4.0 MPa.