Lee et al. (2012) — Flexural Performance and Fiber Distribution of Extruded DFRCC Panel
Citation
Bang Yeon Lee, Byung-Chan Han, Chang-Geun Cho, Yun Yong Kim (2012). Flexural performance and fiber distribution of an extruded DFRCC panel. Computers and Concrete, 10(2), 105–119.
- DOI:
10.12989/cac.2012.10.2.105 - Atlas layer: supporting
- Related Victor Li book chapter: Chapter 5: Processing and Rheology of ECC (also Chapter 11)
- Source PDF:
primary_data/lee-2012-flexural-performance-and-fiber-distribution.pdfIJP00912E_Flexural performance_CAC.pdf` - Extracted text:
secondary_data/full_texts/lee-2012-flexural-performance-and-fiber-distribution_full_text.mdsecondary_data/full_texts/IJP00912E_Flexural performance_CAC_full_text.md` - Source note:
secondary_data/source_notes/lee-2012-flexural-performance-and-fiber-distribution_source_note.mdsecondary_data/source_notes/IJP00912E_Flexural performance_CAC_source_note.md`
Why this paper matters
Provides rigorous experimental and micromechanical analysis of precast extrusion molding for ECC panels, proving that shear-induced fiber alignment ($\theta_{avg} \approx 39.5^\circ$) and a 50 °C 3-day non-autoclave curing cycle yield 35–38 MPa flexural strength and > 9-fold deflection hardening.
Main contribution
- Extrusion Shear Alignment: Confirmed that extrusion aligns short PVA fibers in the longitudinal direction ($\theta = 38^\circ \sim 41^\circ$, average 39.5°), surpassing 2D random ($45.0^\circ$) and 3D random ($57.3^\circ$) orientations.
- High-Strength Thin Panel Manufacturing: Developed a 50 °C 3-day curing regime using sepiolite/CSA-containing DFRCC powder, producing $10\text{ mm}$ thin panels with flexural strength of $35.4 \sim 38.6\text{ MPa}$ (2–4 times cast ECC).
- Micromechanical PSH Fulfillment: Calculated complementary energy ratios ($J_b'/J_{tip} = 7.06 \sim 11.9$), confirming that saturated multiple cracking is maintained under bending.
Evidence summary
- Flexural Strength & Deflection: Maximum flexural strength $F_b = 38.6\text{ MPa}$ with deflection $\delta_b = 6.20\text{ mm}$ ($\delta_b/\delta_{bi} = 9.39$, 11.5 multiple cracks) for mix MX4 (Table 4, Page 113).
- Fiber Alignment: Average fiber orientation $\theta = 39.5^\circ$ with dispersion coefficient $\alpha_f = 0.30 \sim 0.33$ (Table 5, Page 114).
- Toughness Ratio: Energy ratio $J_b'/J_{tip} = 11.9$ for MX4 and $9.93$ for MX3 (Table 6, Page 117).
Linked Atlas nodes
02_concepts/fiber_dispersion.md02_concepts/processing_rheology.md02_concepts/strain_hardening_criteria.md02_concepts/fiber_bridging_law.md
Relationship to Victor Li book
- Primary book anchor remains Victor Li (2019), Engineered Cementitious Composites (ECC).
- Directly supports Chapter 5 (Extrusion processing) and Chapter 11 (Precast applications) by demonstrating that extrusion manufacturing optimizes fiber orientation and composite density.
Claim-evidence rows to add
| Atlas node | Claim | Evidence summary | Page/Figure/Table | Status |
|---|---|---|---|---|
02_concepts/processing_rheology.md |
Precast extrusion molding aligns fibers along the longitudinal axis with an average inclination of 39.5° | Sectional image analysis confirmed $\theta_{avg} = 39.5^\circ$ vs 45.0° (2D) and 57.3° (3D) | Page 114 & 118 / Table 5 / Fig. 11 | verified_from_pdf |
02_concepts/strain_hardening_criteria.md |
Extruded PVA-DFRCC thin panels exhibit flexural strength of 35-38 MPa and deflection hardening ratio > 9 | 4-point bending of $10\text{ mm}$ panels yielded $F_b = 38.6\text{ MPa}$, $\delta_b = 6.20\text{ mm}$ ($\delta_b/\delta_{bi} = 9.39$) | Page 113 & 117 / Table 4 & Table 6 | verified_from_pdf |
02_concepts/fiber_dispersion.md |
Low water-to-binder ratio ($w/c=0.24$) in extrusion excessively increases matrix toughness $J_{tip}$, causing brittle post-crack failure | MX1 panel achieved 50.2 MPa strength but exhibited sudden brittle stress drop due to high $J_{tip}$ | Page 113 & 116 / Table 4 / Fig. 9 | verified_from_pdf |
Verification status
- PDF preserved: yes (in
primary_data/IJP00912E_Flexural performance_CAC.pdf) - Text extracted: yes (PyMuPDF, 15 pages)
- DOI verified: yes (
10.12989/cac.2012.10.2.105) - Page/figure/table verified: yes (all checked in PDF text)
- Claim-evidence matrix ready: yes
Cautions
- Flexural deflection hardening ($\delta_b/\delta_{bi} \approx 9$) is a structural bending metric and must not be confused with direct uniaxial tensile strain capacity ($\epsilon_u$).