Yao et al. (2021) — Development of Engineered Cementitious Composites Using Sea Sand...

Citation

Qiyao Yao, Zuo Li, Chenyu Lu, Linxin Peng, Yuejing Luo, Xiaodan Teng (2021). Development of Engineered Cementitious Composites Using Sea Sand and Metakaolin. Frontiers in Materials, Vol. 8, Article 711872.

DOI: 10.1016/j.fmats.2021.711872
Atlas layer: extension
Related Victor Li book chapter: Chapter 4: Sustainable / Alternative Raw Materials; Chapter 7: Durability
Source PDF: yao-2021-development-of-engineered-cementitious-composites.pdf
Extracted text: atlas/full_text/yao-2021-development-of-engineered-cementitious-composites_full_text.md
Source note: atlas/source_notes/yao-2021-development-of-engineered-cementitious-composites_source_note.md

Why this paper matters

Applies orthogonal experimental design ($L_9(3^4)$) to optimize sea sand and metakaolin engineered cementitious composites (SECC), demonstrating that reactive alumina in metakaolin chemically sequesters sea-sand chlorides into Friedel's salt while achieving compressive strength up to 64.66 MPa and tensile ductility up to 2.40%.

Main contribution

Utilized $L_9(3^4)$ orthogonal array to systematically evaluate sea sand substitution (60–100%), metakaolin content (12–20%), and fly ash ratio (FA/C = 1.2–3.2).
Proved that particle morphology (roundness and sphericity) of sea sand is nearly identical to silica sand, showing aggregate size is the main driver of matrix toughness ($K_m$).
Verified chemical chloride fixation into insoluble Friedel's salt ($C_3A\cdot CaCl_2\cdot 10H_2O$) via XRD diffraction.

Evidence summary

Compressive strength: Ranged between 37.81 and 64.66 MPa (peaked at Mix 8 A3B2C1: 100% sea sand, 16% MK, FA/C = 1.2) (Table 10, page 10).
Direct tensile properties: Tensile strength 2.56–4.58 MPa; tensile strain capacity up to 2.40% in Mix 3 (A1B3C3: 60% sea sand, 20% MK, FA/C = 3.2) (Table 5, page 5, Fig. 3).
Matrix fracture toughness ($K_m$): $0.447\text{ MPa}\cdot\text{m}^{1/2}$ (60% sea sand) to $0.508\text{ MPa}\cdot\text{m}^{1/2}$ (100% sea sand) (Table 7, page 8).
Phase composition: XRD confirmed characteristic diffraction peaks of Friedel's salt ($d = 7.78, 3.88, 3.76, 2.85\ \text{Å}$) in SECC.

Linked Atlas nodes

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

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/green_ecc.md`	Orthogonally optimized sea sand and metakaolin ECC achieves compressive strength up to 64.66 MPa and tensile strain capacity up to 2.40%.	Uniaxial tension and cube compression testing across 9 orthogonal mixes verified peak compressive strength of 64.66 MPa and strain of 2.40%.	Pages 1, 5, 10, Section Results, Tables 5, 10	verified_from_pdf
`02_concepts/durability.md`	Metakaolin addition chemically fixes sea-sand chlorides by promoting Friedel's salt crystallization.	XRD phase analysis confirmed characteristic diffraction peaks of Friedel's salt in metakaolin-bearing SECC.	Pages 1, 10-11, Section XRD, Fig. 8	verified_from_pdf

Verification status

PDF preserved: yes (yao-2021-development-of-engineered-cementitious-composites.pdf)
Text extracted: yes (atlas/full_text/yao-2021-development-of-engineered-cementitious-composites_full_text.md)
DOI verified: yes (10.3389/fmats.2021.711872)
Page/figure/table verified: yes
Claim-evidence matrix ready: yes

Cautions

100% coarse sea sand without adequate fly ash increases matrix fracture toughness, reducing strain hardening capacity.