Choi et al. (2021) — Aspect Ratio Effects of PE Fibers in Slag Composites
Citation
Jeong-Il Choi, Huy Hoàng Nguyễn, Sang Lyul Cha, Mo Li, Bang Yeon Lee (2021). Composite properties of calcium-based alkali-activated slag composites reinforced by different types of polyethylene fibers and micromechanical analysis. Construction and Building Materials, 273, 121760.
- DOI:
10.1016/j.conbuildmat.2020.121760 - Atlas layer: supporting
- Related Victor Li book chapter: Chapter 4: Micromechanics-Based Material Design
- Source PDF:
primary_data/choi-2021-composite-properties-of-calcium-based-alkali-activated.pdfIJP05821E_Composite properties PE_CBM.pdf` - Extracted text:
secondary_data/full_texts/choi-2021-composite-properties-of-calcium-based-alkali-activated_full_text.mdsecondary_data/full_texts/IJP05821E_Composite properties PE_CBM_full_text.md` - Source note:
secondary_data/source_notes/choi-2021-composite-properties-of-calcium-based-alkali-activated_source_note.mdsecondary_data/source_notes/IJP05821E_Composite properties PE_CBM_source_note.md`
Why this paper matters
Systematically isolates the effect of PE fiber aspect ratio (AR-L: 1500, AR-M: 750, AR-S: 375) and curing regimes on calcium-activated slag ECC ($w/b = 0.30$, 1.75 vol. % PE), proving via single-fiber pullout that AR-L fibers develop 76 % higher frictional bond ($\tau_0 = 1.437\text{ MPa}$) and 4.8x higher complementary energy ($J_b' = 119\text{ J/m}^2$), achieving up to 8.75 % direct tensile strain capacity (AR-L-A) and 9.00 MPa tensile strength (AR-L-W) with tight crack widths ($43\text{--}58\ \mu\text{m}$).
Main contribution
- Aspect Ratio Parametric Benchmark: Showed that increasing PE aspect ratio from 375 to 1500 elevated tensile strength from 2.33 to 9.00 MPa and strain capacity from 2.65 % to 8.75 %.
- Single-Fiber Interfacial Characterization: Measured $\tau_0 = 1.437\text{ MPa}$ and $\beta = -0.0474$ for AR-L fibers vs $\tau_0 = 0.818\text{ MPa}$ and $\beta = -0.0017$ for AR-M fibers ($G_d = 0$).
- Theoretical Bridging & PSH Verification: Numerically modeled $\sigma_B(\delta)$ curves, showing that AR-L yields $J_b' = 119\text{ J/m}^2$ (vs $91\text{ J/m}^2$ for AR-M and $25\text{ J/m}^2$ for AR-S), driving 5.2–7.3x more saturated cracks and tighter crack widths ($43.4\ \mu\text{m}$).
Evidence summary
- Direct Tensile Performance (28d):
AR-L-A(Air): $\epsilon_u = 8.75\text{ \%}$, $\sigma_{tu} = 7.67\text{ MPa}$, $\sigma_{fc} = 2.87\text{ MPa}$, Toughness = $0.51\text{ MPa}\cdot\text{m/m}$, SPI = 2.67 (Figs. 5–7, Pages 5–6).AR-L-W(Water): $\epsilon_u = 7.50\text{ \%}$, $\sigma_{tu} = 9.00\text{ MPa}$, $\sigma_{fc} = 3.75\text{ MPa}$, Toughness = $0.53\text{ MPa}\cdot\text{m/m}$, SPI = 2.40.AR-M-A: $\epsilon_u = 8.20\text{ \%}$, $\sigma_{tu} = 4.50\text{ MPa}$;AR-M-W: $\epsilon_u = 6.45\text{ \%}$, $\sigma_{tu} = 4.26\text{ MPa}$.AR-S-A: $\epsilon_u = 4.65\text{ \%}$, $\sigma_{tu} = 2.75\text{ MPa}$;AR-S-W: $\epsilon_u = 2.65\text{ \%}$, $\sigma_{tu} = 2.33\text{ MPa}$.- 28-Day Compressive Strength: AR-L-W = $42.8\text{ MPa}$ vs AR-L-A = $35.1\text{ MPa}$ (Fig. 4, Page 4).
- Crack Microstructure: AR-L-A crack width = $43.4\ \mu\text{m}$, AR-L-W crack width = $58.2\ \mu\text{m}$ (Fig. 9, Page 8).
- Micromechanical & Energy Parameters: $\tau_0 = 1.437\text{ MPa}$ (AR-L) vs $0.818\text{ MPa}$ (AR-M); $J_b' = 119\text{ J/m}^2$ (AR-L) vs $25\text{ J/m}^2$ (AR-S) (Tables 5–7, Page 9).
Linked Atlas nodes
02_concepts/interface_properties.md02_concepts/strain_hardening_criteria.md04_material_systems/green_ecc.md05_experiments/crack_width_distribution.md05_experiments/single_fiber_pullout.md05_experiments/direct_tensile_test.md
Relationship to Victor Li book
- Primary book anchor remains Victor Li (2019), Engineered Cementitious Composites (ECC).
- Directly supports Chapter 4 (Micromechanics-Based Material Design) by verifying that fiber aspect ratio is the primary lever scaling complementary energy ($J_b' = 119\text{ J/m}^2$) and driving pseudo strain-hardening in cementless slag geopolymers.
Claim-evidence rows to add
| Atlas node | Claim | Evidence summary | Page/Figure/Table | Status |
|---|---|---|---|---|
02_concepts/interface_properties.md |
AR-L PE fibers (aspect ratio 1500) exhibit 76 % higher frictional bond strength ($\tau_0 = 1.437\text{ MPa}$) than AR-M fibers (aspect ratio 750) | Single-fiber pullout tests measured $\tau_0 = 1.437\text{ MPa}$ for AR-L vs $0.818\text{ MPa}$ for AR-M | Page 121760:8 & 10 / Table 5 / Fig. 10 | verified_from_pdf |
02_concepts/strain_hardening_criteria.md |
Higher fiber aspect ratio scales complementary energy to 119 $\text{J/m}^2$ (4.8x over AR-S), sustaining 7.50–8.75 % direct tensile ductility | Numerical integration calculated $J_b' = 119\text{ J/m}^2$ for AR-L vs $25\text{ J/m}^2$ for AR-S | Page 121760:9 / Table 7 / Fig. 11 | verified_from_pdf |
04_material_systems/green_ecc.md |
Air curing promotes higher tensile strain capacity (8.75 %) with tighter crack widths (43.4 $\mu\text{m}$), while water curing maximizes tensile strength (9.00 MPa) | Tension tests recorded $\epsilon_u = 8.75\text{ \%}$ for AR-L-A and $\sigma_{tu} = 9.00\text{ MPa}$ for AR-L-W | Page 121760:5 & 8 / Figs. 5, 6, 8, 9 | verified_from_pdf |
Verification status
- PDF preserved: yes (in
primary_data/IJP05821E_Composite properties PE_CBM.pdf) - Text extracted: yes (PyMuPDF, 10 pages)
- DOI verified: yes (
10.1016/j.conbuildmat.2020.121760) - Page/figure/table verified: yes (all checked in PDF text)
- Claim-evidence matrix ready: yes
Cautions
- Water curing elevates compressive strength (42.8 MPa) and matrix cracking strength, which slightly lowers tensile ductility (7.50 % vs 8.75 % in air curing).