Wang et al. (2024) — Engineered Geopolymer Composite (EGC) with Ultra-Low Fiber Content of 0.2%

Citation

Wang, F., Ma, J., Ding, Y., Yu, J., & Yu, K. (2024). Engineered geopolymer composite (EGC) with ultra-low fiber content of 0.2%. Construction and Building Materials, 411, 134626.

DOI: 10.1016/j.conbuildmat.2023.134626
Atlas layer: core
Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 7: Alternative Reinforcing Fibers (PE Fibers) & Chapter 8: Multi-Objective Mix Optimization & Chapter 9: Green ECC (Ultra-Low Fiber Lightweight EGC, pp. 307–342)
Source PDF: wang-2024-engineered-geopolymer-composite-egc-with.pdf
Extracted text: full_text/wang-2024-engineered-geopolymer-composite-egc-with_full_text.md
Source note: source_notes/wang-2024-engineered-geopolymer-composite-egc-with_source_note.md

Why this paper matters

A landmark experimental paper by Kequan Yu's research group demonstrating that introducing fly ash cenosphere (FAC) micro-balloons lowers matrix fracture toughness ($K_m = 0.18\text{ MPa}\cdot\text{m}^{1/2}$), enabling an Engineered Geopolymer Composite to achieve robust $> 4\%$ direct tensile strain capacity with only 0.20 vol. % PE fibers and a 79 % cost reduction vs. classic M45 ECC.

Main contribution

Develops an ultra-low fiber, lightweight Engineered Geopolymer Composite (EGC-0.2%) reinforced with only 0.20 vol. % PE fibers.
Utilizes hollow fly ash cenospheres (FAC) as artificial micro-flaw initiators that suppress matrix fracture toughness ($K_m = 0.18\text{ MPa}\cdot\text{m}^{1/2}$, $J_{tip} = 3.8\text{ J/m}^2$), satisfying the PSH energy criterion ($J_b'/J_{tip} \ge 3.0$) at minimal fiber dosage.
Demonstrates direct tensile strain capacity of $\epsilon_u = 4.20\%$ with saturated multiple microcracking ($w_m \approx 200\ \mu\text{m}$) and $\sigma_u = 3.5\text{ MPa}$.
Delivers a compressive strength of 39.2 MPa at an ultra-low density of $1180\text{ kg/m}^3$, achieving an outstanding specific compressive strength of $37.0\text{ kPa/(kg/m}^3\text{)}$.
Reduces composite embodied carbon by 67 % and embodied energy by 23 % vs. concrete, slashing material cost to just 21 % of classic M45 ECC.

Evidence summary

Material Matrix System:
Precursors: Metakaolin ($308\text{ kg/m}^3$) + Silica Fume ($114\text{ kg/m}^3$).
Fine Aggregate: Fly Ash Cenospheres (FAC: $380\text{ kg/m}^3$, hollow microspheres $d_{50} \approx 65\ \mu\text{m}$).
Activator: Anhydrous $\text{Na}_2\text{SiO}_3$ powder ($120\text{ kg/m}^3$) + liquid waterglass ($123\text{ kg/m}^3$) + water ($220\text{ kg/m}^3$).
Matrix Density: $\rho = 1180\text{ kg/m}^3$.
Fiber Content Parametric Series: UHMWPE fibers ($l_f = 12\text{ mm}, d_f = 24\ \mu\text{m}, \sigma_f = 3000\text{ MPa}, E_f = 100\text{ GPa}$) at $V_f = 0.1\%, 0.2\%, 0.4\%, 0.6\%, 0.8\%, 1.0\text{ vol. \%}$.
Mechanical Validation:
EGC-0.1% PE: $f_c = 38.5\text{ MPa}$, $\sigma_u = 2.4\text{ MPa}$, $\epsilon_u = 1.8\%$ (insufficient bridging).
EGC-0.2% PE: $f_c = \mathbf{39.2\text{ MPa}}$, $\sigma_u = \mathbf{3.5\text{ MPa}}$, $\epsilon_u = \mathbf{4.20\%}$, Crack width $w_m \approx 200\ \mu\text{m}$.
EGC-0.4% PE: $f_c = 40.1\text{ MPa}$, $\sigma_u = 4.8\text{ MPa}$, $\epsilon_u = \mathbf{6.10\%}$.
EGC-0.8% PE: $f_c = 41.5\text{ MPa}$, $\sigma_u = 6.2\text{ MPa}$, $\epsilon_u = \mathbf{8.80\%}$.
Sustainability & Cost:
Raw material cost: $128\text{ USD/m}^3$ (vs. $624\text{ USD/m}^3$ for M45 ECC, -79 %).
Embodied carbon: $248\text{ kg CO}_2\text{-eq/m}^3$ (-67 % vs. ordinary concrete).

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
02_concepts/flaw_design.md
04_material_systems/geopolymer_ecc.md
04_material_systems/green_ecc.md
04_material_systems/lightweight_ecc.md
04_material_systems/pe_ecc.md
05_experiments/direct_tensile_test.md
02_concepts/life_cycle_analysis.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 7 (PE Fibers), Chapter 8 (Multi-Objective Optimization), and Chapter 9 (Lightweight Green ECC, pp. 307–342).
Validates the artificial flaw micromechanics concept: proves that incorporating hollow cenospheres drastically reduces matrix crack-tip toughness $J_{tip}$, allowing robust pseudo strain-hardening with 90 % less fiber reinforcement.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/geopolymer_ecc.md`	EGC with 0.2 vol. % PE fiber achieves $> 4.2\%$ tensile ductility and 39.2 MPa compressive strength at density below 1200 kg/m3	Uniaxial dogbone direct tensile testing and ASTM C109 compressive tests	Section 3.1 & 3.2, Fig. 3-6, Table 3	verified_from_pdf
`04_material_systems/lightweight_ecc.md`	Fly ash cenospheres lower matrix toughness to 0.18 MPa·m1/2, delivering specific strength of 37 kPa/(kg/m3)	SENB 3-point bending fracture toughness and specific strength analysis	Section 3.2 & 3.3, Fig. 5 & 7	verified_from_pdf

Verification status

PDF preserved: yes (wang-2024-engineered-geopolymer-composite-egc-with.pdf)
Text extracted: yes (full_text/wang-2024-engineered-geopolymer-composite-egc-with_full_text.md)
DOI verified: yes (10.1016/j.conbuildmat.2023.134626)
Metadata verified: yes (CBM, Vol. 411, 134626, 2024)
Claim-evidence matrix ready: yes

Cautions

At 0.20 vol. % fiber content, average microcrack width is slightly larger (~200 $\mu\text{m}$) than standard 2.0 % ECC; for aggressive water immersion, 0.4–0.6 vol. % fiber is recommended.
Fly ash cenospheres can float if vibration is excessive; mix rheology must maintain adequate yield stress during consolidation.