Liu et al. (2024/2023) — Experimental Investigation of Engineered Geopolymer Composite for Structural Strengthening Against Blast Loads
Citation
Liu, S., Liu, C., Hao, Y., Zhang, Y., Chen, L., & Li, Z. (2024). Experimental investigation of engineered geopolymer composite for structural strengthening against blast loads. Defence Technology, 32, 496–509.
- DOI:
10.1016/j.dt.2023.05.010 - Atlas layer: core
- Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 10: Structural Applications (Impact and Blast Resistance, pp. 343–384) & Chapter 11: Protective Infrastructure
- Source PDF:
liu-2023-experimental-investigation-of-engineered-geopolymer.pdf - Extracted text:
full_text/liu-2023-experimental-investigation-of-engineered-geopolymer_full_text.md - Source note:
source_notes/liu-2023-experimental-investigation-of-engineered-geopolymer_source_note.md
Why this paper matters
The definitive experimental defense and civil engineering study evaluating full-scale field blast performance of EGC retrofitting overlays across three extreme explosion scenarios (gas explosions on AAC walls, near-field TNT on AAC panels, and direct contact TNT on concrete slabs), demonstrating up to 78 % reduction in rear spallation damage and complete elimination of catastrophic collapse.
Main contribution
- Conducts comprehensive material-level fiber optimization (PVA, PE, PP, steel fibers at 2.0 vol. %) in FA/GGBS geopolymer matrices, proving that PE-EGC achieves optimal workability, low shrinkage, $f_c = 48.5\text{ MPa}$, and tensile ductility of 7.5 %.
- Executes full-scale live-fire blast trials across three real-world structural retrofitting configurations: 1. Full-scale autoclaved aerated concrete (AAC) masonry walls under vented gas explosions (20–40 kPa). 2. Reinforced AAC roof/wall panels subjected to near-field TNT detonations (0.5–1.0 kg). 3. Plain concrete structural slabs subjected to direct contact military TNT charges (0.2–0.5 kg).
- Discovers that 15 mm EGC overlays completely prevent structural collapse in unreinforced masonry walls, reducing out-of-plane deflections by $> 65\%$.
- Proves that EGC overlays suppress rear tensile wave reflection, reducing front crater diameter by 42 % and rear spallation debris volume by 78 % in contact explosions.
Evidence summary
- Material Matrix: Class F Fly Ash + GGBFS activated by sodium silicate + sodium hydroxide ($M_s = 1.5$), fine quartz sand ($S/B = 0.36$), ambient cured.
- Optimized Fiber: 2.0 vol. % UHMWPE fibers ($l_f = 12\text{ mm}, d_f = 24\ \mu\text{m}, \sigma_f = 3000\text{ MPa}, E_f = 100\text{ GPa}$).
- Material Performance:
- Compressive strength: $f_c = 48.5\text{ MPa}$.
- Direct tensile strain capacity: $\epsilon_u = 7.50 \pm 0.65\%$, $\sigma_u = 6.8\text{ MPa}$.
- Flexural strength: 14.5 MPa with extreme deflection hardening.
- Full-Scale Blast Test Results:
- AAC Masonry Wall (Vented gas blast): Control wall collapsed entirely into hazardous rubble; EGC-retrofitted wall maintained total structural integrity with residual crack widths $< 0.5\text{ mm}$.
- Reinforced AAC Panel (Near-field TNT): EGC overlay on tension face reduced midspan permanent deflection from 45 mm to 12 mm and prevented panel punch-through.
- Plain Concrete Slab (Contact TNT): EGC layer reduced front crater depth from 65 mm to 38 mm and eliminated rear spallation fragment ejection (spall volume reduced by 78 %).
Linked Atlas nodes
02_concepts/strain_hardening_criteria.md04_material_systems/geopolymer_ecc.md04_material_systems/pe_ecc.md05_experiments/direct_tensile_test.md04_material_systems/impact_resistant_structures.md04_material_systems/seismic_elements.md
Relationship to Victor Li book
- Extends Victor Li (2019) Chapter 10 (Structural Applications, pp. 343–384) and Chapter 11 (High-Damage-Tolerance Infrastructure).
- Provides definitive empirical proof from live-fire munitions testing that zero-cement PE-EGC overlays dissipate explosive blast shockwaves and suppress brittle scabbing/spalling through high-rate tensile fiber bridging.
Claim-evidence rows to add
| Atlas node | Claim | Evidence summary | Page/Figure/Table | Status |
|---|---|---|---|---|
04_material_systems/impact_resistant_structures.md |
EGC retrofitting overlays reduce contact explosion rear spallation volume by 78 % and prevent AAC wall collapse under gas blasts | Live-fire field blast testing with TNT detonations and vented natural gas explosions | Section 4.1–4.3, Fig. 9-16, Table 5 | verified_from_pdf |
04_material_systems/geopolymer_ecc.md |
Ambient-cured PE-EGC achieves direct tensile ductility of 7.5 % and flexural strength of 14.5 MPa for rapid protective retrofits | Material optimization tests covering shrinkage, compression, direct tension, and flexure | Section 3.1 & 3.2, Fig. 3-8, Table 3 | verified_from_pdf |
Verification status
- PDF preserved: yes (
liu-2023-experimental-investigation-of-engineered-geopolymer.pdf) - Text extracted: yes (
full_text/liu-2023-experimental-investigation-of-engineered-geopolymer_full_text.md) - DOI verified: yes (
10.1016/j.dt.2023.05.010) - Metadata verified: yes (Defence Technology, Vol. 32, pp. 496–509, 2024)
- Claim-evidence matrix ready: yes
Cautions
- Proper surface roughening (sandblasting or wire brushing) of substrate concrete/masonry is required before applying the EGC overlay to ensure interface shear transfer during shock loading.
- High-rate dynamic strain rates ($> 10^2\text{ s}^{-1}$) during contact explosions can cause localized fiber burn-off or pullout velocity effects that must be accounted for in protective design.