Kang et al. (2016) — Hybrid Effects of Steel Fiber & Microfiber in UHPC
Citation
Su-Tae Kang, Jeong-Il Choi, Kyung-Taek Koh, Kang Seok Lee, Bang Yeon Lee (2016). Hybrid effects of steel fiber and microfiber on the tensile behavior of ultra-high performance concrete. Composite Structures, 145, 37–42.
- DOI:
10.1016/j.compstruct.2016.02.075 - Atlas layer: supporting
- Related Victor Li book chapter: Chapter 10: High-Strength and Ultra-High Performance ECC (also Chapter 4)
- Source PDF:
primary_data/kang-2016-hybrid-effects-of-steel-fiber.pdfIJP02516E_Hybrid effects of steel fiber_COST.pdf` - Extracted text:
secondary_data/full_texts/kang-2016-hybrid-effects-of-steel-fiber_full_text.mdsecondary_data/full_texts/IJP02516E_Hybrid effects of steel fiber_COST_full_text.md` - Source note:
secondary_data/source_notes/kang-2016-hybrid-effects-of-steel-fiber_source_note.mdsecondary_data/source_notes/IJP02516E_Hybrid effects of steel fiber_COST_source_note.md`
Why this paper matters
Demonstrates the synergistic effects of combining 0.2 mm straight steel fibers with high-strength polyethylene (PE) microfibers in 150 MPa UHPC, achieving simultaneous improvements in tensile strength (16.21 MPa) and tensile strain capacity (0.99 %).
Main contribution
- Steel-PE Hybrid Synergy: Found that replacing 33 % of steel fibers with 18 mm PE microfibers in 150 MPa UHPC increases first cracking strength to 11.13 MPa (+14 %), ultimate tensile strength to 16.21 MPa (+13 %), and tensile strain capacity to 0.99 % (+39 %).
- Microfiber Specificity: Proved that while basalt microfibers maximize first cracking strength (13.42 MPa, +37 %) due to strong chemical bonding, they cause premature rupture and reduce ductility (0.22 %). PVA microfibers also reduced tensile strength in this 150 MPa matrix.
- Crack Width Progression: Confirmed that PE microfibers sustain fiber bridging resistance up to larger crack widths (126 $\mu\text{m}$), promoting multiple cracking.
Evidence summary
- Direct Tensile Response: First crack $11.13\text{ MPa}$, ultimate strength $16.21\text{ MPa}$, strain capacity $0.99\text{ \%}$ for mix S1.0-PE0.5 (Table 7, Page 40).
- Compressive Strength: $149\text{ MPa}$ (S1.5 control), $142\text{ MPa}$ (S1.0-PE0.5), $128\text{ MPa}$ (S1.0-B0.5) (Table 6, Page 39).
- Crack Characteristics: S1.5 crack width = $54\ \mu\text{m}$ (single localized crack) vs S1.0-PE0.5 crack width = $126\ \mu\text{m}$ (multiple micro-cracking) (Fig. 4 & 5, Page 41).
Linked Atlas nodes
04_material_systems/high_strength_ecc.md02_concepts/fiber_hybridization.md02_concepts/strain_hardening_criteria.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 10 (UHP-ECC) and Chapter 4 (Hybrid fiber design) by quantifying dual-scale fiber bridging in ultra-dense, low $w/b$ (0.20) matrices.
Claim-evidence rows to add
| Atlas node | Claim | Evidence summary | Page/Figure/Table | Status |
|---|---|---|---|---|
02_concepts/fiber_hybridization.md |
Replacing 33 % steel fiber with PE microfiber in 150 MPa UHPC increases tensile strength to 16.21 MPa and ductility to 0.99 % | S1.0-PE0.5 achieved $\sigma_{tu} = 16.21\text{ MPa}$ (+13 %) and $\epsilon_u = 0.99\text{ \%}$ (+39 % vs S1.5) | Page 37 & 42 / Table 7 / Fig. 2 | verified_from_pdf |
04_material_systems/high_strength_ecc.md |
Basalt microfiber in UHPC increases first crack strength to 13.42 MPa (+37 %) but reduces strain capacity to 0.22 % | S1.0-B0.5 reached first crack $13.42\text{ MPa}$ but experienced severe post-crack strain-softening | Page 39 & 40 / Table 7 / Fig. 2 | verified_from_pdf |
02_concepts/fiber_hybridization.md |
PE microfibers sustain crack bridging resistance up to 126 $\mu\text{m}$, delaying macro-crack localization in UHPC | Optical microscopy confirmed multiple micro-cracks and $126\ \mu\text{m}$ crack opening at peak stress | Page 41 / Fig. 4 & Fig. 5 | verified_from_pdf |
Verification status
- PDF preserved: yes (in
primary_data/IJP02516E_Hybrid effects of steel fiber_COST.pdf) - Text extracted: yes (PyMuPDF, 6 pages)
- DOI verified: yes (
10.1016/j.compstruct.2016.02.075) - Page/figure/table verified: yes (all checked in PDF text)
- Claim-evidence matrix ready: yes
Cautions
- Tensile strain capacity is 0.99 % (typical for UHPC); do not confuse with standard ECC ductile strain capacity ($\epsilon_u > 2-3\text{ \%}$).