Lee et al. (2017) — Effects of a defoamer on the compressive strength...

Citation

Yun Lee, Jeong-Il Choi, Hyeong-Ki Kim, Bang Yeon Lee (2017). Effects of a defoamer on the compressive strength and tensile behavior of alkali-activated slag-based cementless composite reinforced by polyethylene fiber. Composite Structures, Vol. 172, pp. 166-172.

DOI: 10.1016/j.compstruct.2017.03.095
Atlas layer: extension
Related Victor Li book chapter: Chapter 4: Matrix and Flaw Tailoring; Chapter 7: Green ECC
Source PDF: lee-2017-effects-of-a-defoamer-on.pdf
Extracted text: atlas/full_text/lee-2017-effects-of-a-defoamer-on_full_text.md
Source note: atlas/source_notes/lee-2017-effects-of-a-defoamer-on_source_note.md

Why this paper matters

Demonstrates that controlling entrapped air voids with a small amount of defoamer (0.1–0.2 wt%) in PE-reinforced alkali-activated slag composites enhances compressive strength by 20% (to 41.4 MPa), increases tensile strength by 27% (to 8.82 MPa), and expands tensile ductility to 7.18%.

Main contribution

Evaluated the influence of chemical defoamer dosage (0%, 0.1%, 0.2 wt% of binder) on the pore structure, compressive strength, and uniaxial tensile behavior of PE-AAS composites.
Proved that eliminating large macro-pores (>1 $\mu\text{m}$) elevates the stress performance index from 2.04 to 2.52 and increases tensile toughness by 47%.
Achieved tensile strain capacity of 7.18% and tensile strength of 8.82 MPa in mix D2 with 1.75 vol% PE fibers.

Evidence summary

Tensile strain capacity: $5.83 \pm 0.81\%$ (D0, 0% defoamer), $6.48 \pm 0.42\%$ (D1, 0.1% defoamer), $7.18 \pm 0.46\%$ (D2, 0.2% defoamer) (Table 5, page 168).
Tensile strength: $6.93\text{ MPa}$ (D0), $8.74\text{ MPa}$ (D1), $8.82\text{ MPa}$ (D2) (Table 5, page 168).
Compressive strength: $34.5\text{ MPa}$ (D0), $41.3\text{ MPa}$ (D1, +20.0%), $41.4\text{ MPa}$ (D2) (Table 4, page 168).
Toughness: $0.30\text{ MPa mm/mm}$ (D0) $\rightarrow 0.44\text{ MPa mm/mm}$ (D2, +47.0%).
Crack characteristics: 44.5–52.3 cracks, crack spacing 1.56–1.86 mm, crack width 92.6–132.8 $\mu\text{m}$.

Linked Atlas nodes

04_material_systems/green_ecc.md
02_concepts/extreme_ductility_ecc.md
02_concepts/flaw_design.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`	Adding 0.1–0.2 wt% defoamer to PE-AASC increases compressive strength by 20% and tensile strain capacity up to 7.18%.	Compressive strength increased from 34.5 to 41.4 MPa and tensile ductility reached 7.18% in D2.	Pages 166, 168, Section 3.1 & 3.2, Tables 4, 5	verified_from_pdf
`02_concepts/flaw_design.md`	Defoamer-induced macro-pore elimination raises the stress performance index to 2.52 and tensile toughness by 47%.	The stress performance index reached 2.52, increasing tensile energy absorption to 0.44 MPa mm/mm.	Page 168, Table 5, Fig. 2	verified_from_pdf

Verification status

PDF preserved: yes (lee-2017-effects-of-a-defoamer-on.pdf)
Text extracted: yes (atlas/full_text/lee-2017-effects-of-a-defoamer-on_full_text.md)
DOI verified: yes (10.1016/j.compstruct.2017.03.095)
Page/figure/table verified: yes
Claim-evidence matrix ready: yes

Cautions

Adding defoamer beyond 0.1 wt% yields no further increase in compressive strength and slightly widens crack width.
Evaluated on paste matrix without fine aggregate.