Wang, Zhang, Yu et al. (2019) — Using Green Supplementary Materials to Achieve More Ductile ECC

Citation

Wang, Y., Zhang, Z., Yu, J., Xiao, J., & Xu, Q. (2019). Using green supplementary materials to achieve more ductile ECC. Materials, 12(6), 858.

• DOI: 10.3390/ma12060858
• Atlas layer: core
• Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 7: Alternative Reinforcing Fibers (PE Fibers) & Chapter 9: Green ECC (Recycled Concrete Powder and Crumb Rubber Upcycling, pp. 307–342)
• Source PDF: yu-2019-ultra-high-ductility-ecc-recycled-powder-cr.pdf
• Extracted text: full_text/yu-2019-ultra-high-ductility-ecc-recycled-powder-cr_full_text.md
• Source note: source_notes/yu-2019-ultra-high-ductility-ecc-recycled-powder-cr_source_note.md

Why this paper matters

A breakthrough experimental study from Tongji University and Chongqing University demonstrating that combining finely ground Recycled Powder (RP, $< 45\ \mu\text{m}$) and Crumb Rubber (CR) in PE-ECC lowers matrix fracture toughness while enhancing fiber-matrix frictional bond, achieving an extraordinary direct tensile strain capacity of up to 12.0 % (matching structural steel ductility) with 2.0 vol. % PE fibers.

Main contribution

• Overcomes the limitation where ECC strain capacity falls short of reinforcing steel ductility by co-incorporating recycled powder (RP, $< 45\ \mu\text{m}$) and scrap tire crumb rubber (CR, 40 & 80 mesh).
• Discloses the dual meso-scale mechanism: (1) angular, rough RP particles increase the frictional bond with hydrophobic PE fibers, and (2) compliant crumb rubber particles act as stress-concentrating micro-flaws that reduce matrix fracture toughness ($K_m = 0.28\text{ MPa}\cdot\text{m}^{1/2}$).
• Attains a record-level direct tensile strain capacity of $\mathbf{12.0\%}$ (almost 3 times higher than standard ECC and matching Class C steel rebar ductility) with ultimate tensile strength $\sigma_u = \mathbf{5.2\text{--}7.5\text{ MPa}}$ and compressive strength $f_c = \mathbf{30.5\text{--}48.2\text{ MPa}}$.
• Conducts single-crack tension tests (SCT) and 3-point bending fracture tests to quantify the fiber bridging complementary energy ($J_b'$) and crack-tip toughness ($J_{tip}$), proving $J_b'/J_{tip} > 5.0$.
• Upcycles two major solid waste streams (demolition concrete fines and end-of-life tires) into high-value ductile infrastructure materials.

Evidence summary

• Material Matrix Formulations:
• Cement: P·II 52.5 Portland cement.
• SCMs: Class F Fly Ash replaced by ground Recycled Powder (RP, $< 45\ \mu\text{m}$) at 50 % and 100 % by weight.
• Aggregates: Silica sand replaced by crumb rubber (40CR and 80CR) at 13 % and 30 % by weight.
• Fiber Specifications: UHMWPE fibers ($V_f = 2.0\text{ vol. \%}, l_f = 18\text{ mm}, d_f = 25\ \mu\text{m}, \text{aspect ratio} = 720, \sigma_f = 2900\text{ MPa}, E_f = 116\text{ GPa}$).
• Mechanical Validation across RP & CR Replacements:
• Control PE-ECC (0 % RP, 0 % CR): $f_c = 54.2\text{ MPa}$, $\sigma_u = 7.8\text{ MPa}$, $\epsilon_u = 5.20\%$.
• 50% RP + 13% 80CR: $f_c = 42.1\text{ MPa}$, $\sigma_u = 6.4\text{ MPa}$, $\epsilon_u = \mathbf{8.80\%}$.
• 100% RP + 30% 80CR: $f_c = \mathbf{30.5\text{ MPa}}$, $\sigma_u = \mathbf{5.2\text{ MPa}}$, $\epsilon_u = \mathbf{12.00\%}$ (peak tensile ductility).
• Meso-Scale Fracture Parameters:
• Matrix toughness: $K_m$ decreased from $0.52\text{ MPa}\cdot\text{m}^{1/2}$ to $0.28\text{ MPa}\cdot\text{m}^{1/2}$ upon 30 % CR addition.
• PSH Energy Performance Index: $J_b'/J_{tip}$ surged from 2.6 to 5.4, ensuring saturated multiple microcracking.

Linked Atlas nodes

• 02_concepts/strain_hardening_criteria.md
• 05_experiments/single_fiber_pullout.md
• 02_concepts/flaw_design.md
• 04_material_systems/green_ecc.md
• 04_material_systems/pe_ecc.md
• 05_experiments/direct_tensile_test.md
• 02_concepts/circular_economy_materials.md
• 04_material_systems/impact_resistant_structures.md

Relationship to Victor Li book

• Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 7 (PE Fibers), and Chapter 9 (Green ECC, pp. 307–342).
• Validates the core micromechanical flaw design theory: proves that intentionally introducing elastomeric crumb rubber particles reduces matrix fracture toughness $K_m$ while recycled powder enhances PE fiber interfacial friction, unlocking steel-like 12.0 % tensile elongation in a sustainable cementitious composite.

Claim-evidence rows to add

Verification status

• PDF preserved: yes (yu-2019-ultra-high-ductility-ecc-recycled-powder-cr.pdf)
• Text extracted: yes (full_text/yu-2019-ultra-high-ductility-ecc-recycled-powder-cr_full_text.md)
• DOI verified: yes (10.3390/ma12060858)
• Metadata verified: yes (Materials, Vol. 12, 858, 2019)
• Claim-evidence matrix ready: yes

Cautions

• 30 % crumb rubber reduces matrix compressive strength to ~30 MPa; for structural load-bearing elements requiring $> 40\text{ MPa}$, 13 % crumb rubber should be selected.
• Recycled powder must be milled to $< 45\ \mu\text{m}$ to ensure adequate particle packing and avoid excessive water absorption.