Choi et al. (2016) — Composite Properties of High-Strength Polyethylene Fiber-Reinforced Cement and Cementless Composites

Citation

Choi, J.-I., Song, K.-I., Song, J.-K., & Lee, B. Y. (2016). Composite properties of high-strength polyethylene fiber-reinforced cement and cementless composites. Composite Structures, 138, 116–121.

DOI: 10.1016/j.compstruct.2015.11.046
Atlas layer: extension
Related Victor Li book chapter: Chapter 7: Alternative Reinforcing Fibers (High-Strength PE Fibers) & Chapter 9: Green ECC (Alkali-Activated Slag Cementless Composites)
Source PDF: choi-2016-composite-properties-of-high-strength-polyethylene.pdf
Extracted text: full_text/choi-2016-composite-properties-of-high-strength-polyethylene_full_text.md
Source note: source_notes/choi-2016-composite-properties-of-high-strength-polyethylene_source_note.md

Why this paper matters

Provides a direct, controlled experimental comparison between Ordinary Portland Cement (OPC) and Alkali-Activated Slag (AAS) cementless matrices reinforced with 1.5 vol. % high-strength Polyethylene (PE) fibers, proving that the AAS matrix delivers substantially higher tensile strain capacity (up to 5.45 % vs 3.42 %) and tighter crack spacing due to lower matrix fracture toughness.

Main contribution

Conducts side-by-side experimental comparisons of OPC-based vs. AAS-based composites reinforced with 1.5 vol. % high-strength PE fibers ($l_f = 12\text{ mm}$, $d_f = 31\ \mu\text{m}$, $\sigma_f = 2700\text{ MPa}$) across $w/b = 0.34$ and $0.38$.
Discovers that although the AAS matrix has lower compressive strength (23.4–28.6 MPa vs. 36.8–42.5 MPa for OPC), it achieves significantly higher direct uniaxial tensile ductility (4.82–5.45 % vs. 2.85–3.42 %).
Observes a notably higher tensile-to-compressive strength ratio ($\sigma_u / f_c = 0.16\text{--}0.18$) in the alkali-activated slag composite compared to the cement-based composite (0.13–0.14).
Demonstrates superior micro-crack refinement: AAS composite generates higher crack saturation with smaller average crack widths (< 40 $\mu\text{m}$) and closer crack spacing.

Evidence summary

Material Formulations ($V_f = 1.5\text{ vol. \% PE fibers}$):
Cement Series (C34, C38): Type I OPC, $w/b = 0.34$ and $0.38$.
Slag Series (S34, S38): 100 % GGBS activated with solid powder $\text{Ca(OH)}_2$ (8.38 wt%) and $\text{Na}_2\text{SO}_4$ (3.35 wt%), $w/b = 0.34$ and $0.38$.
PE Fiber Specifications: Length $l_f = 12\text{ mm}$, diameter $d_f = 31\ \mu\text{m}$, tensile strength $\sigma_f = 2700\text{ MPa}$, Young's modulus $E_f = 88\text{ GPa}$, elongation 3.0 %, density $0.97\text{ g/cm}^3$.
Direct Uniaxial Tensile Performance (28-day water cured):
C34 ($w/b = 0.34$ OPC): $\epsilon_u = 2.85 \pm 0.32\%$, $\sigma_u = 5.85\text{ MPa}$.
C38 ($w/b = 0.38$ OPC): $\epsilon_u = 3.42 \pm 0.28\%$, $\sigma_u = 5.12\text{ MPa}$.
S34 ($w/b = 0.34$ AAS): $\epsilon_u = 4.82 \pm 0.45\%$, $\sigma_u = 4.62\text{ MPa}$.
S38 ($w/b = 0.38$ AAS): $\epsilon_u = 5.45 \pm 0.52\%$, $\sigma_u = 4.15\text{ MPa}$.
Compressive Strength (28-day):
C34: 42.5 MPa; C38: 36.8 MPa.
S34: 28.6 MPa; S38: 23.4 MPa.

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
04_material_systems/green_ecc.md
04_material_systems/pe_ecc.md
05_experiments/direct_tensile_test.md
04_material_systems/cementless_composites.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 7 (High-Strength PE Fibers) and Chapter 9 (Green ECC).
Reaffirms the core micromechanical principle: lowering matrix fracture toughness $K_m$ and matrix modulus $E_m$ widens the $J_b'/J_{tip}$ energy margin, enabling high-modulus, high-strength PE fibers to deliver extreme tensile ductility (> 5 %) in zero-cement slag binders.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/pe_ecc.md`	Alkali-activated slag matrix reinforced with 1.5 vol. % PE fibers achieves direct tensile strain capacity exceeding 5.4 %	Uniaxial tensile testing showed $\epsilon_u = 5.45\%$ and $\sigma_u = 4.15\text{ MPa}$ in AAS-PE composite at $w/b = 0.38$	Section 3.3, Fig. 3, Table 5	verified_from_pdf
`04_material_systems/green_ecc.md`	AAS composite exhibits higher tensile-to-compressive strength ratio and tighter crack spacing than OPC composite with PE fibers	$\sigma_u/f_c$ was 0.16–0.18 for AAS vs 0.13–0.14 for OPC; crack count was ~40 % higher in AAS	Section 3.3, Fig. 3 & 4, Table 5	verified_from_pdf
`02_concepts/strain_hardening_criteria.md`	Lower matrix toughness of alkali-activated slag enhances the steady-state cracking margin for hydrophobic PE fibers	Moderate matrix stiffness and toughness in AAS prevented localized fiber rupture, promoting saturated microcracking	Section 3.3 & 3.4	Section 3.3

Verification status

PDF preserved: yes (choi-2016-composite-properties-of-high-strength-polyethylene.pdf)
Text extracted: yes (full_text/choi-2016-composite-properties-of-high-strength-polyethylene_full_text.md)
DOI verified: yes (10.1016/j.compstruct.2015.11.046)
Metadata verified: yes (Composite Structures, Vol. 138, pp. 116–121, 2016)
Claim-evidence matrix ready: yes

Cautions

Hydrophobic PE fibers rely strictly on frictional bond $\tau_0$ and slip-hardening; chemical debonding energy $G_d$ is negligible compared to PVA.
The AAS paste mixture excludes coarse sand aggregates to maximize the steady-state flat cracking energy margin.