Wang et al. (2024) — Fully Recycled Engineered Geopolymer Composite: Mechanical Properties and Sustainability Assessment
Citation
Wang, F., Ding, Y., Nishiwaki, T., Zhang, Z., Yu, J., & Yu, K. (2024). Fully recycled engineered geopolymer composite: Mechanical properties and sustainability assessment. Journal of Cleaner Production, 471, 143382.
- DOI:
10.1016/j.jclepro.2024.143382 - 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 (Fully Recycled Concrete Powder and Sand Upcycling, pp. 307–342)
- Source PDF:
wang-2024-fully-recycled-engineered-geopolymer.pdf - Extracted text:
full_text/wang-2024-fully-recycled-engineered-geopolymer_full_text.md - Source note:
source_notes/wang-2024-fully-recycled-engineered-geopolymer_source_note.md
Why this paper matters
A breakthrough study from Tongji University and Tohoku University maximizing the simultaneous upcycling of two concrete demolition waste streams—Recycled Concrete Powder (RCP) as binder precursor and Recycled Fine Sand (RFS) as 100 % aggregate—creating a sustainable geopolymer composite that achieves 84 MPa compressive strength, 7.4 MPa tensile strength, and 8.10 % tensile strain capacity.
Main contribution
- Overcomes the traditional performance degradation of recycled concrete composites through the synergistic co-utilization of Recycled Concrete Powder (RCP, $< 75\ \mu\text{m}$) and Recycled Fine Sand (RFS, $< 0.6\text{ mm}$).
- Formulates a high-performance Engineered Geopolymer Composite incorporating 50 % RCP (replacing GGBFS/fly ash) and 100 % RFS (replacing virgin quartz sand).
- Discloses the dual micromechanical mechanism: (1) lower reactivity of RCP reduces matrix toughness to promote saturated multiple cracking, while (2) alkali-activated surface reactions on RFS establish strong interfacial aggregate-paste bonding, restoring compressive load capacity.
- Sets a new performance benchmark for recycled geopolymer composites: compressive strength $f_c = \mathbf{84.0\text{ MPa}}$, ultimate tensile strength $\sigma_u = \mathbf{7.4\text{ MPa}}$, and direct tensile ductility $\epsilon_u = \mathbf{8.10\%}$.
- Reduces embodied carbon by 57 % and embodied energy by 16 % compared to classic M45 ECC.
Evidence summary
- Material Matrix System:
- Precursor Blend: Ground granulated blast-furnace slag (GGBS) + Fly ash + Recycled concrete powder (RCP: $0\%\text{--}50\%\text{ substitution}, d_{50} < 75\ \mu\text{m}$).
- Fine Aggregate: 100 % Recycled fine sand (RFS, $d < 0.6\text{ mm}, \text{sand/binder} = 0.36$).
- Activator: Liquid sodium silicate ($\text{Na}_2\text{O}\cdot 2.25\text{SiO}_2$) + $\text{NaOH}$ solution ($M_s = 1.4\text{--}1.6$).
- Fiber Specifications: UHMWPE fibers ($V_f = 2.0\text{ vol. \%}, l_f = 12\text{ mm}, d_f = 24\ \mu\text{m}, \sigma_f = 3000\text{ MPa}, E_f = 100\text{ GPa}$).
- Mechanical Validation across RCP Replacements (with 100 % RFS):
0% RCP + 100% RFS: $f_c = 96.2\text{ MPa}$, $\sigma_u = 8.8\text{ MPa}$, $\epsilon_u = 5.20\%$.30% RCP + 100% RFS: $f_c = 88.5\text{ MPa}$, $\sigma_u = 7.9\text{ MPa}$, $\epsilon_u = 6.80\%$.50% RCP + 100% RFS: $f_c = \mathbf{84.0\text{ MPa}}$, $\sigma_u = \mathbf{7.4\text{ MPa}}$, $\epsilon_u = \mathbf{8.10\%}$ (optimum high-ductility formulation).- Mineralogical & Microstructural Analysis:
- XRD and TG confirmed coexistence of 3D cross-linked C-(N)-A-S-H gel and layered double hydroxide (LDH / hydrotalcite phases).
- MIP showed refined sub-50 nm mesopore distribution, preventing coarse void formation.
- Sustainability Analysis:
- Embodied carbon: $342\text{ kg CO}_2\text{-eq/m}^3$ (-57 % vs. M45 ECC).
- Embodied energy: $3.92\text{ GJ/m}^3$ (-16 % vs. M45 ECC).
Linked Atlas nodes
02_concepts/strain_hardening_criteria.md02_concepts/flaw_design.md04_material_systems/geopolymer_ecc.md04_material_systems/green_ecc.md04_material_systems/high_strength_ecc.md04_material_systems/pe_ecc.md05_experiments/direct_tensile_test.md02_concepts/circular_economy_materials.md02_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 Design), and Chapter 9 (Green ECC, pp. 307–342).
- Proves that industrial and demolition waste streams can be tailored to satisfy Victor Li's PSH energy condition: shows that the moderate reactivity of recycled concrete powder actively prevents matrix over-embrittlement, enabling ultra-high tensile strain capacity (8.1 %) even at 84 MPa compressive strength.
Claim-evidence rows to add
| Atlas node | Claim | Evidence summary | Page/Figure/Table | Status |
|---|---|---|---|---|
04_material_systems/geopolymer_ecc.md |
Fully recycled EGC with 50 % RCP and 100 % RFS achieves 84 MPa compressive strength, 7.4 MPa tensile strength, and 8.1 % strain capacity | Uniaxial tensile dogbone testing and ASTM C39 compressive testing | Section 3.2–3.4, Fig. 4-8, Table 4 | verified_from_pdf |
02_concepts/circular_economy_materials.md |
Synergistic co-utilization of RCP and RFS cuts embodied carbon by 57 % vs. M45 ECC while upcycling 100 % waste concrete sand | Cradle-to-gate life cycle carbon and energy inventory analysis | Section 3.6, Fig. 13 & 14, Table 6 | verified_from_pdf |
Verification status
- PDF preserved: yes (
wang-2024-fully-recycled-engineered-geopolymer.pdf) - Text extracted: yes (
full_text/wang-2024-fully-recycled-engineered-geopolymer_full_text.md) - DOI verified: yes (
10.1016/j.jclepro.2024.143382) - Metadata verified: yes (J. Clean. Prod., Vol. 471, 143382, 2024)
- Claim-evidence matrix ready: yes
Cautions
- RCP content exceeding 50 % causes excessive slump loss and delays setting time due to high unreacted quartz filler fractions.
- RFS contains attached mortar that increases activator water absorption; activator liquid batching must be adjusted for aggregate surface moisture.