Huang et al. (2021) — Seawater Sea-Sand Engineered/Strain-Hardening Cementitious Composites (ECC/SHCC): Assessment and Modeling of Crack Characteristics

Citation

Huang, B.-T., Wu, J.-Q., Yu, J., Dai, J.-G., Leung, C. K. Y., & Li, V. C. (2021). Seawater sea-sand engineered/strain-hardening cementitious composites (ECC/SHCC): Assessment and modeling of crack characteristics. Cement and Concrete Research, 140, 106292.

DOI: 10.1016/j.cemconres.2020.106292
Atlas layer: core
Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 5: Multiple Cracking Behavior & Chapter 9: Green ECC (Seawater Sea-Sand Systems) & Chapter 10: Marine Durability
Source PDF: huang-2021-seawater-sea-sand-engineered-strain-hardening.pdf
Extracted text: full_text/huang-2021-seawater-sea-sand-engineered-strain-hardening_full_text.md
Source note: source_notes/huang-2021-seawater-sea-sand-engineered-strain-hardening_source_note.md

Why this paper matters

A landmark collaborative study from HK PolyU, HKUST, Sun Yat-Sen University, and the University of Michigan (Victor C. Li and Christopher Leung). Establishes the material design, micromechanics, and probabilistic crack evolution laws for Seawater Sea-Sand ECC (SS-ECC) for direct offshore and island infrastructure, proving that raw seawater and unwashed sea-sand sustain direct tensile strain capacities up to 7.2 % and crack widths $< 50\ \mu\text{m}$.

Main contribution

Develops Seawater Sea-Sand ECC (SS-ECC) using raw natural seawater, unwashed sea-sand ($D_{max} = 1.18\text{ mm}, 2.36\text{ mm}, 4.75\text{ mm}$), and high-strength PE fibers ($l_f = 6, 12, 18\text{ mm}$, $V_f = 1.0\text{--}2.0\%$).
Formulates a unified Five-Dimensional (5D) Representation to holistically evaluate ECC: compressive strength, tensile strength, tensile strain capacity, mean crack width ($w_m$), and crack width coefficient of variation ($COV_w$).
Develops and validates a Probabilistic Crack Evolution Model using Weibull and log-normal distributions to predict the stochastic evolution of crack widths as a function of tensile strain.
Quantifies micromechanical parameters via single-fiber pullout and notched beam fracture tests ($K_m$), proving that sea-sand up to $D_{max} = 2.36\text{ mm}$ maintains robust pseudo strain-hardening ($J_b'/J_{tip} > 3$) and delivers tensile strain capacity exceeding 5.0 %.

Evidence summary

Material Matrix: Unwashed natural sea-sand (coarse particles up to 4.75 mm), artificial seawater (3.5 wt% salinity), slag-cement binder, and PE fibers ($d_f = 24\ \mu\text{m}$, $\sigma_f = 3000\text{ MPa}$, $E_f = 100\text{ GPa}$).
Mechanical Properties (28 days):
Compressive strength: 52.5 to 78.4 MPa (and up to > 130 MPa in ultra-high-strength versions).
Uniaxial tensile strain capacity ($\epsilon_u$): $3.5\%\text{ to }7.2\%$ (optimum mix L18-V2.0-S1 achieves $\epsilon_u = 7.2\%$).
Ultimate tensile strength ($\sigma_u$): 5.1 to 8.5 MPa.
Crack Characteristics & Evolution:
Saturated crack widths: Mean crack width $w_m$ remains tightly controlled at 35–55 $\mu\text{m}$ at 1.0 % tensile strain, and $< 80\ \mu\text{m}$ at ultimate failure.
Probabilistic model: Two-parameter Weibull and log-normal distributions reliably estimate the probability of exceeding allowable crack width limits ($w \le 50\ \mu\text{m}$) for marine corrosion control.

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
02_concepts/fiber_bridging_law.md
05_experiments/single_fiber_pullout.md
04_material_systems/green_ecc.md
04_material_systems/pe_ecc.md
04_material_systems/seawater_sea_sand_ecc.md
05_experiments/direct_tensile_test.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 5 (Multiple Cracking), and Chapter 9 (Green ECC).
Breakthrough in resource sustainability: eliminates the requirement for scarce freshwater and manufactured silica sand in coastal environments, showing that raw seawater salts accelerate early strength while PE fibers prevent chloride-induced composite degradation when paired with non-corrosive FRP rebar.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/seawater_sea_sand_ecc.md`	Seawater sea-sand ECC (SS-ECC) achieves direct tensile strain capacity up to 7.2 % and tensile strength up to 8.5 MPa	Uniaxial tensile testing on dumbbell specimens across sand sizes (up to 4.75 mm) and fiber lengths (6–18 mm)	Section 3.1 & 3.2, Fig. 3-6, Table 4	verified_from_pdf
`02_concepts/strain_hardening_criteria.md`	Sea-sand with $D_{max} \le 2.36\text{ mm}$ preserves $J_b'/J_{tip} > 3.0$, enabling steady-state multiple cracking	Matrix fracture toughness ($K_m$) and single-fiber pullout tests confirmed PSH energy criteria satisfaction	Section 4.4, Fig. 13-15, Table 7	verified_from_pdf
`04_material_systems/seawater_sea_sand_ecc.md`	Probabilistic Weibull model accurately predicts the stochastic evolution of crack width distribution in SS-ECC under increasing tensile strain	Statistical regression on 24.2-megapixel high-resolution digital image crack mapping	Section 4.2 & 4.3, Fig. 8-12, Table 6	verified_from_pdf

Verification status

PDF preserved: yes (huang-2021-seawater-sea-sand-engineered-strain-hardening.pdf)
Text extracted: yes (full_text/huang-2021-seawater-sea-sand-engineered-strain-hardening_full_text.md)
DOI verified: yes (10.1016/j.cemconres.2020.106292)
Metadata verified: yes (Cement and Concrete Research, Vol. 140, 106292, 2021)
Claim-evidence matrix ready: yes

Cautions

Due to internal chlorides from seawater/sea-sand, SS-ECC must be paired with non-corrosive reinforcement (such as FRP bars, stainless steel, or basalt FRP) rather than conventional carbon steel rebar.
Coarse sea-sand ($D_{max} = 4.75\text{ mm}$) increases matrix fracture toughness $K_m$, reducing tensile strain capacity to ~3.5 %.