Trindade et al. (2020) — Tensile Behavior of Strain-Hardening Geopolymer Composites (SHGC) Under Impact Loading

Citation

Trindade, A. C. C., Heravi, A. A., Curosu, I., Liebscher, M., Silva, F. de A., & Mechtcherine, V. (2020). Tensile behavior of strain-hardening geopolymer composites (SHGC) under impact loading. Cement and Concrete Composites, 113, 103703.

DOI: 10.1016/j.cemconcomp.2020.103703
Atlas layer: core
Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 7: Alternative Reinforcing Fibers (UHMWPE vs. PVA Fibers) & Chapter 11: Structural Applications (Dynamic Impact and Protective Structures, pp. 385–420)
Source PDF: trindade-2020-tensile-behavior-of-strain-hardening-geopolymer.pdf
Extracted text: full_text/trindade-2020-tensile-behavior-of-strain-hardening-geopolymer_full_text.md
Source note: source_notes/trindade-2020-tensile-behavior-of-strain-hardening-geopolymer_source_note.md

Why this paper matters

A landmark international experimental study by TU Dresden and PUC-Rio investigating the direct uniaxial tensile impact response of PVA- and UHMWPE-reinforced strain-hardening geopolymer composites using a gravity-driven Split Hopkinson Tension Bar (SHTB) up to strain rates of $300\text{ s}^{-1}$, proving that PE-SHGC delivers superior dynamic tensile strength (16.8 MPa) and energy dissipation without fiber rupture.

Main contribution

First comprehensive investigation of the direct uniaxial dynamic tensile response of strain-hardening geopolymer composites (SHGC) at strain rates up to $\dot{\epsilon} = 300\text{ s}^{-1}$ using a Split Hopkinson Tension Bar (SHTB).
Compares metakaolin geopolymer matrices reinforced with 2.0 vol. % PVA vs. UHMWPE fibers at both composite and single-fiber scales.
Utilizes high-speed stereo cameras (up to 100,000 fps) and 3D Digital Image Correlation (DIC) to track dynamic crack opening displacements and multiple cracking saturation during impact.
Performs dynamic single-fiber pullout tests in a miniature SHTB, discovering that PVA fibers suffer dynamic rate-induced interfacial embrittlement and fiber snapping, whereas UHMWPE fibers maintain ductile slip-hardening.
Demonstrates that PE-SHGC achieves a dynamic tensile strength of 16.8 MPa ($\text{DIF} = 2.37$), dynamic strain capacity of 4.1 %, and volumetric energy dissipation of $580\text{ kJ/m}^3$, outperforming standard cement-based SHCC.

Evidence summary

Material Matrix: Pure metakaolin ($\text{Al}2\text{O}_3\cdot 2\text{SiO}_2$) activated by waterglass solution ($\text{Na}_2\text{O}\cdot 2\text{SiO}_2\cdot 11\text{H}_2\text{O}$), fine quartz sand ($d, S/B = 0.50$).} = 0.2\text{ mm
Fiber Types Evaluated:
PVA Fibers: Kuraray K-II REC15, $l_f = 12\text{ mm}, d_f = 40\ \mu\text{m}, \sigma_f = 1600\text{ MPa}, E_f = 41\text{ GPa}$, 1.2 wt% oil coating.
UHMWPE Fibers: Dyneema SK60, $l_f = 12\text{ mm}, d_f = 20\ \mu\text{m}, \sigma_f = 3000\text{ MPa}, E_f = 88\text{ GPa}$.
Volume Fraction: $V_f = 2.0\text{ vol. \%}$.
SHTB Dynamic Tensile Performance ($\dot{\epsilon} = 100\text{--}160\text{ s}^{-1}$):
PE-SHGC: Dynamic tensile strength $\sigma_{u,dyn} = \mathbf{16.8\text{ MPa}}$ (vs. 7.1 MPa quasi-static, $\text{DIF} = \mathbf{2.37}$); dynamic strain capacity $\epsilon_{u,dyn} = \mathbf{4.10\%}$; energy dissipation = $\mathbf{580\text{ kJ/m}^3}$.
PVA-SHGC: Dynamic tensile strength $\sigma_{u,dyn} = 8.9\text{ MPa}$ (vs. 4.8 MPa quasi-static, $\text{DIF} = 1.85$); dynamic strain capacity dropped to $1.20\%$ due to dynamic fiber rupture.
Dynamic Single-Fiber Pullout: Miniature SHTB tests showed that dynamic loading increases chemical/frictional bonding by $> 80\%$, driving PVA fibers past their tensile strength limit while PE fibers utilize high slip-hardening without rupture.

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
05_experiments/single_fiber_pullout.md
04_material_systems/geopolymer_ecc.md
04_material_systems/green_ecc.md
04_material_systems/pe_ecc.md
04_material_systems/pva_ecc.md
05_experiments/direct_tensile_test.md
05_experiments/single_fiber_pullout.md
04_material_systems/impact_resistant_structures.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 7 (PE and PVA Fibers), and Chapter 11: Dynamic Impact and Protective Structures (pp. 385–420).
Validates the rate-dependent micromechanics of strain-hardening composites: proves that hydrophobic UHMWPE fibers avoid the high-rate interfacial embrittlement typical of PVA fibers, ensuring metal-like ductility under severe dynamic impact.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/impact_resistant_structures.md`	UHMWPE-SHGC achieves 16.8 MPa dynamic tensile strength and 4.1 % strain capacity under high strain-rate SHTB impact ($\dot{\epsilon} = 160\text{ s}^{-1}$)	Split Hopkinson Tension Bar (SHTB) testing with high-speed stereo DIC	Section 3.2, Fig. 8-11, Table 3	verified_from_pdf
`04_material_systems/pe_ecc.md`	Dynamic single-fiber pullout confirms PE fibers maintain slip-hardening under impact, avoiding the fiber rupture observed in PVA fibers	Miniature SHTB single-fiber pullout tests and ESEM fractography	Section 3.3, Fig. 12-15	verified_from_pdf

Verification status

PDF preserved: yes (trindade-2020-tensile-behavior-of-strain-hardening-geopolymer.pdf)
Text extracted: yes (full_text/trindade-2020-tensile-behavior-of-strain-hardening-geopolymer_full_text.md)
DOI verified: yes (10.1016/j.cemconcomp.2020.103703)
Metadata verified: yes (Cem. Concr. Compos., Vol. 113, 103703, 2020)
Claim-evidence matrix ready: yes

Cautions

PVA fibers in geopolymer matrices undergo rate-dependent bond strengthening that triggers premature fiber snapping under strain rates $> 50\text{ s}^{-1}$; UHMWPE fibers are required for impact-resistant applications.
Metakaolin geopolymer slurries have high viscosity; high-shear planetary mixing is necessary to disperse 2.0 vol. % PE fibers uniformly.