Wei et al. (2024) — Microstructure, mechanical properties and interaction mechanism of seawater...

Citation

Jiaying Wei, Linyuwen Ke, Peng Wang, Weiwen Li, Christopher K.Y. Leung (2024). Microstructure, mechanical properties and interaction mechanism of seawater sea-sand engineered cementitious composite (SS-ECC) with Glass Fiber Reinforced Polymer (GFRP) bar. Composite Structures, Vol. 343, Article 118302.

DOI: 10.1016/j.compstruct.2024.118302
Atlas layer: extension
Related Victor Li book chapter: Chapter 4: Special ECCs / Marine Infrastructure; Chapter 6: Structural Applications / Reinforcement Bond
Source PDF: wei-2024-microstructure-mechanical-properties-and-interaction.pdf
Extracted text: atlas/full_text/wei-2024-microstructure-mechanical-properties-and-interaction_full_text.md
Source note: atlas/source_notes/wei-2024-microstructure-mechanical-properties-and-interaction_source_note.md

Why this paper matters

Investigates the interfacial bond-slip mechanics, microstructural transition zone (ITZ), and mechanical properties of GFRP bars embedded in normal-strength (PVA) and high-strength (PE) seawater sea-sand ECCs, proving that seawater accelerates early hydration and reduces ITZ thickness by 19.2%, which enhances GFRP bond strength by 28.3% and fracture energy by 22.6% in normal-strength SS-ECC.

Main contribution

Evaluated non-corrosive GFRP rebar ($d_b = 9.52\text{ mm}$, $f_t = 1256\text{ MPa}$) bond performance in marine seawater sea-sand ECCs.
Revealed Friedel's salt crystallization and ITZ densification in normal-strength PVA-ECC, boosting bond strength $\tau_{max}$ from $10.6\text{ MPa}$ to $13.6\text{ MPa}$ (28.3% increase).
Identified divergent failure modes: matrix shear crushing in normal-strength PVA-ECC versus GFRP bar interlaminar surface delamination in 120 MPa high-strength PE-ECC.

Evidence summary

Microstructural ITZ: Median porous transition zone thickness was $0.44\ \mu\text{m}$ in SS-PVA (vs $0.51\ \mu\text{m}$ in FR-PVA) and $0.30\ \mu\text{m}$ in SS-PE (Section 3.1, Fig. 8).
Physical & Compressive properties: SS-PVA reduced porosity by 10.3%; 28d compressive strength reached $40\text{--}45\text{ MPa}$ (PVA) and $110\text{--}120\text{ MPa}$ (PE) (Section 3.2, 3.3.1, Figs. 11, 12).
Direct tensile properties: SS-PVA achieved $\sigma_u \approx 4.5\text{ MPa}$, $\varepsilon_u \approx 2.5\%$; SS-PE achieved $\sigma_u \approx 14.0\text{ MPa}$, $\varepsilon_u \approx 4.4\%$ (Section 3.3.2, Figs. 13, 14).
GFRP Pull-out bond: SS-PVA increased $\tau_{max}$ by 28.3% and $G_f$ by 22.6%; high-strength PE-ECC bond strength reached $>20\text{ MPa}$ limited by bar interlaminar resin peeling (Section 3.3.3, Figs. 15, 18).

Linked Atlas nodes

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

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/green_ecc.md`	Seawater in normal-strength PVA-ECC accelerates early cement hydration via Friedel's salt formation, reducing ITZ thickness by 19.2% and enhancing GFRP bar bond strength by 28.3%.	BSE image analysis, EDS line scans, and ASTM D7913 pull-out tests verified ITZ refinement and bond strength gain.	Pages 1, 8, 16, Section 3.1.2, 3.3.3 & Abstract, Figs. 8, 16, 18	verified_from_pdf
`04_material_systems/high_strength_ecc.md`	In high-strength SS-ECC (120 MPa, 2.0 vol% PE), GFRP pullout failure is governed by bar interlaminar resin peeling rather than matrix crushing, rendering seawater effects negligible.	Pullout failure morphology and SEM BSE imaging confirmed GFRP interlaminar shear delamination at >20 MPa bond stress.	Pages 13, 14, 16, Section 3.3.3.1, Figs. 15c-d, 18a	verified_from_pdf

Verification status

PDF preserved: yes (wei-2024-microstructure-mechanical-properties-and-interaction.pdf)
Text extracted: yes (atlas/full_text/wei-2024-microstructure-mechanical-properties-and-interaction_full_text.md)
DOI verified: yes (10.1016/j.compstruct.2024.118302)
Page/figure/table verified: yes
Claim-evidence matrix ready: yes

Cautions

Seawater matrix densification causes a minor reduction in 28-day tensile strain capacity (3.2% down to 2.5% in PVA-ECC).