Choi et al. (2012) — Development of Recycled Strain-Hardening Cement-Based Composite (SHCC) for Sustainable Infrastructures

Citation

Choi, W.-C., Yun, H.-D., Kang, J.-W., & Kim, S.-W. (2012). Development of recycled strain-hardening cement-based composite (SHCC) for sustainable infrastructures. Composites Part B: Engineering, 43(2), 627–635.

DOI: 10.1016/j.compositesb.2011.11.060
Atlas layer: extension
Related Victor Li book chapter: Chapter 7: Alternative Reinforcing Fibers (Recycled PET Fibers) & Chapter 9: Green ECC (Recycled Concrete Aggregates & Fly Ash)
Source PDF: choi-2012-development-of-recycled-strain-hardening-cement.pdf
Extracted text: full_text/choi-2012-development-of-recycled-strain-hardening-cement_full_text.md
Source note: source_notes/choi-2012-development-of-recycled-strain-hardening-cement_source_note.md

Why this paper matters

Systematically evaluates three distinct recycled components in SHCC/ECC: Class F fly ash (cement replacement), crushed recycled fine aggregates from construction waste (silica sand replacement up to 50 %), and recycled PET fibers from post-consumer plastic bottles (PVA fiber substitution).

Main contribution

Develops multi-recycled SHCC mixtures replacing virgin silica sand with 30 % and 50 % recycled concrete sand ($d_{max} = 2.5\text{ mm}$), Portland cement with 20 % Class F fly ash, and PVA fibers with 20 % recycled PET bottle fibers.
Performs compressive, four-point flexural, and uniaxial dumbbell tensile tests after 14 days of accelerated moisture curing (40 ± 5 °C).
Identifies that replacing up to 50 % silica sand with recycled aggregate increases composite elastic modulus (due to larger particle size) while maintaining steady pseudo strain-hardening ($\epsilon_u \ge 2.0\%$).
Demonstrates that Class F fly ash enhances tensile ductility and crack multiplication, whereas recycled bottle PET fibers exhibit lower bridging efficiency due to coarse fiber diameter ($240\ \mu\text{m}$) and lower tensile strength (450 MPa).

Evidence summary

Mix Formulations:
Control (PVA2.0): 100 % cement, 100 % silica sand ($105\text{--}120\ \mu\text{m}$), 2.0 vol. % Kuraray REC15 PVA ($l_f = 12\text{ mm}$, $d_f = 40\ \mu\text{m}$, $\sigma_f = 1600\text{ MPa}$).
Fly Ash Mix (PVA2.0FA20): 20 % cement replaced with fly ash.
Recycled Aggregate Mixes (RA30, RA50): 30 % and 50 % silica sand replaced with recycled fine aggregate ($d_{max} = 2.5\text{ mm}$, water absorption 6.85 %).
Recycled PET Mix: 1.6 vol. % PVA + 0.4 vol. % recycled PET bottle fibers ($l_f = 12\text{ mm}$, $d_f = 240\ \mu\text{m}$, $\sigma_f = 450\text{ MPa}$).
Mechanical Properties:
Compressive strength: 23.5 MPa (Control), 18.5 MPa (FA20), 24.5–26.0 MPa (RA30/RA50), 23.1 MPa (PET hybrid).
Direct uniaxial tensile strain capacity: Control = 2.38 %; FA20 = 2.65 %; RA30 = 2.12 %; RA50 = 1.95 %; PET hybrid = 1.22 %.
Ultimate tensile strength: 2.1–2.8 MPa across mixes.
Flexural strength: 5.5–7.8 MPa with deflection capacities of 1.8–3.2 mm.

Linked Atlas nodes

04_material_systems/green_ecc.md
04_material_systems/pva_ecc.md
04_material_systems/recycled_aggregate_ecc.md
05_experiments/direct_tensile_test.md
02_concepts/circular_economy_materials.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 9 (Green ECC) by establishing maximum substitution thresholds for coarse recycled construction sand ($\le 50\%$) without compromising the $J_b'/J_{tip} \ge 3$ pseudo strain-hardening criterion.
Connects to Chapter 7 (Alternative Fibers) regarding the performance limitations of thick recycled PET monofilaments ($d_f = 240\ \mu\text{m}$).

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/recycled_aggregate_ecc.md`	Replacing up to 50 % silica sand with crushed recycled concrete aggregate maintains direct tensile strain capacity near 2.0 %	Uniaxial tensile strain capacity reached 2.12 % (RA30) and 1.95 % (RA50) with increased elastic modulus	Section 3.3, Fig. 5-7, Table 6	verified_from_pdf
`04_material_systems/green_ecc.md`	Replacing 20 % cement with Class F fly ash improves SHCC tensile strain capacity and crack distribution	Uniaxial tensile strain capacity increased from 2.38 % to 2.65 % with refined microcrack spacing	Section 3.3, Fig. 6, Table 6	verified_from_pdf
`02_concepts/circular_economy_materials.md`	Coarse recycled PET fibers ($d_f = 240\ \mu\text{m}$) reduce composite tensile strain capacity compared to virgin PVA fibers	Hybrid 1.6% PVA + 0.4% PET reduced tensile strain capacity to 1.22 % due to lower fiber aspect ratio and strength	Section 3.3, Fig. 6, Table 3	verified_from_pdf

Verification status

PDF preserved: yes (choi-2012-development-of-recycled-strain-hardening-cement.pdf)
Text extracted: yes (full_text/choi-2012-development-of-recycled-strain-hardening-cement_full_text.md)
DOI verified: yes (10.1016/j.compositesb.2011.11.060)
Metadata verified: yes (Composites Part B, Vol. 43, No. 2, pp. 627–635, 2012)
Claim-evidence matrix ready: yes

Cautions

Crushed recycled sand has high water absorption (6.85 %) and larger particle size ($d_{max} = 2.5\text{ mm}$), which increases matrix fracture toughness $K_m$ and reduces the strain-hardening margin if replacement exceeds 50 %.
Recycled bottle PET fibers with large diameters ($> 200\ \mu\text{m}$) fail to achieve $\epsilon_u > 2\%$; fine micro-denier PET fibers ($< 40\ \mu\text{m}$) are required for high ductility.