Yu et al. (2018) — Tensile Performance of Sustainable Strain-Hardening Cementitious Composites with Hybrid PVA and Recycled PET Fibers

Citation

Yu, J., Yao, J., Lin, X., Li, H., Lam, J. Y. K., Leung, C. K. Y., Sham, I. M. L., & Shih, K. (2018). Tensile performance of sustainable Strain-Hardening Cementitious Composites with hybrid PVA and recycled PET fibers. Cement and Concrete Research, 107, 110–123.

DOI: 10.1016/j.cemconres.2018.02.013
Atlas layer: core
Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 7: Alternative Reinforcing Fibers (Recycled Polymeric Fibers) & Chapter 9: Green ECC (Recycled PET Fiber Hybridization, pp. 307–342)
Source PDF: yu-2018-tensile-performance-of-sustainable-strain-hardening.pdf
Extracted text: full_text/yu-2018-tensile-performance-of-sustainable-strain-hardening_full_text.md
Source note: source_notes/yu-2018-tensile-performance-of-sustainable-strain-hardening_source_note.md

Why this paper matters

A landmark experimental and micromechanical study from HKUST, NAMI, and PolyU demonstrating that up to 50 % of expensive virgin PVA fibers can be substituted with surface-treated recycled polyethylene terephthalate (PET) fibers from post-consumer plastic bottles, retaining robust pseudo strain-hardening ($\epsilon_u = 3.62\%$, $w_m < 85\ \mu\text{m}$) and long-term durability while cutting fiber cost by 43 %.

Main contribution

Develops a micromechanical hybrid fiber bridging model $\sigma(\delta)$ and a semi-empirical strain capacity prediction formula for hybrid-fiber SHCCs.
Evaluates the replacement of virgin oiled PVA fibers with recycled PET fibers (0 %, 25 %, 50 %, 75 %, 100 %) at a total volume fraction of $V_f = 2.0\text{ vol. \%}$.
Applies an alkaline surface treatment (NaOH etching) to recycled PET fibers to enhance chemical adhesion and interfacial friction with the cementitious matrix.
Proves that a 50:50 hybrid blend (1.0 vol. % PVA + 1.0 vol. % recycled PET) achieves direct tensile ductility of $\epsilon_u = 3.62\%$ and tensile strength of $\sigma_u = 4.3\text{ MPa}$ at 28 days, maintaining $\epsilon_u = 2.75\%$ after accelerated hot-water aging (60 °C).
Achieves a 43 % reduction in fiber material cost and a 38 % reduction in carbon footprint compared to standard PVA-ECC.

Evidence summary

Material Matrix System:
Type I Portland cement + Class F Fly Ash (FA/C = 2.2), fine silica sand ($d_{50} = 100\ \mu\text{m}$), $w/b = 0.25$.
Fiber Specifications ($V_f = 2.0\text{ vol. \%}$ total):
Virgin PVA Fibers: Kuraray REC15, $l_f = 12\text{ mm}, d_f = 40\ \mu\text{m}, \sigma_f = 1600\text{ MPa}, E_f = 41\text{ GPa}$, 1.2 wt% oil.
Recycled PET Fibers: Crushed post-consumer bottles, $l_f = 10\text{ mm}, d_f = 33\ \mu\text{m}, \sigma_f = 850\text{ MPa}, E_f = 14\text{ GPa}$, NaOH etched.
Mechanical Validation across Hybrid Ratios:
100% PVA (Control): $\sigma_u = 4.8\text{ MPa}$, $\epsilon_u = 4.20\%$, $w_m = 65\ \mu\text{m}$.
25% PET + 75% PVA: $\sigma_u = 4.5\text{ MPa}$, $\epsilon_u = 3.90\%$, $w_m = 72\ \mu\text{m}$.
50% PET + 50% PVA: $\sigma_u = \mathbf{4.3\text{ MPa}}$, $\epsilon_u = \mathbf{3.62\%}$, $w_m = \mathbf{82\ \mu\text{m}}$ (optimum economic hybrid).
100% PET: $\sigma_u = 3.4\text{ MPa}$, $\epsilon_u = \mathbf{2.10\%}$, $w_m = 120\ \mu\text{m}$.
Long-Term Durability (Accelerated Aging at 60 °C):
50 % PET hybrid SHCC retained $\epsilon_u = 2.75\%$ with zero fiber chemical degradation.
Economic and Carbon Evaluation:
Fiber cost decreased from $480\text{ USD/m}^3$ to $274\text{ USD/m}^3$ (-43 %).

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
05_experiments/single_fiber_pullout.md
04_material_systems/green_ecc.md
04_material_systems/pva_ecc.md
05_experiments/direct_tensile_test.md
02_concepts/circular_economy_materials.md
02_concepts/life_cycle_analysis.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 7 (Polymeric Fiber Reinforcement), and Chapter 9 (Green ECC, pp. 307–342).
Validates Victor Li's multi-fiber micromechanics: demonstrates that pairing high-modulus PVA fibers (which supply early crack bridging) with low-cost recycled PET fibers (which maintain tail-end pullout friction) satisfies PSH criteria while radically lowering the composite cost structure.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/green_ecc.md`	50:50 hybrid PVA/recycled PET fiber SHCC achieves 3.62 % tensile strain capacity and 4.3 MPa tensile strength	Uniaxial direct tensile tests, crack width tracking, and DIC	Section 4.1 & 4.2, Fig. 5-8, Table 4	verified_from_pdf
`02_concepts/circular_economy_materials.md`	Substituting 50 % of virgin PVA fibers with recycled plastic PET fibers reduces fiber cost by 43 % and carbon footprint by 38 %	Cost modeling and lifecycle carbon emissions analysis	Section 5, Fig. 13 & 14, Table 6	verified_from_pdf

Verification status

PDF preserved: yes (yu-2018-tensile-performance-of-sustainable-strain-hardening.pdf)
Text extracted: yes (full_text/yu-2018-tensile-performance-of-sustainable-strain-hardening_full_text.md)
DOI verified: yes (10.1016/j.cemconres.2018.02.013)
Metadata verified: yes (CCR, Vol. 107, pp. 110–123, 2018)
Claim-evidence matrix ready: yes

Cautions

Untreated recycled PET fibers have weak mechanical anchoring and low surface energy; alkaline surface etching is necessary to promote adequate frictional bond.
Pure 100 % PET fiber composites exhibit lower tensile strength (3.4 MPa) and wider crack widths (~120 $\mu\text{m}$); fiber hybridization with PVA is recommended for structural applications.