Dias & Thaumaturgo (2005) — Fracture Toughness of Geopolymeric Concretes Reinforced with Basalt Fibers

Citation

Dias, D. P., & Thaumaturgo, C. (2005). Fracture toughness of geopolymeric concretes reinforced with basalt fibers. Cement & Concrete Composites, 27(1), 49–54.

DOI: 10.1016/j.cemconcomp.2004.02.044
Atlas layer: extension
Related Victor Li book chapter: Chapter 2: Matrix Fracture Energy & Chapter 7: Alternative Reinforcing Fibers (Basalt Fibers) & Chapter 9: Green ECC (Geopolymer Binders)
Source PDF: dias-2005-fracture-toughness-of-geopolymeric-concretes.pdf
Extracted text: full_text/dias-2005-fracture-toughness-of-geopolymeric-concretes_full_text.md
Source note: source_notes/dias-2005-fracture-toughness-of-geopolymeric-concretes_source_note.md

Why this paper matters

An early landmark study on geopolymer concrete fracture mechanics, evaluating the Mode I critical stress intensity factor ($K_{Ic}$) and critical crack mouth opening displacement ($CMOD_c$) of metakaolin-based poly(siloxo-sialate) geopolymer concretes reinforced with 0.5–1.0 vol. % basalt fibers compared to Portland cement concrete.

Main contribution

Evaluates the fracture toughness and crack growth resistance of metakaolin-based geopolymer concrete (PSS) vs. high early strength Portland cement concrete across three basalt fiber dosages (0 %, 0.5 %, 1.0 % by volume).
Conducts three-point bending fracture tests on 18 notched beams ($150 \times 150 \times 500\text{ mm}$, notch depth ratio $a_0/h = 0.2$).
Demonstrates that plain and fiber-reinforced geopolymer concretes possess superior fracture toughness ($K_{Ic}$) and higher deformation tolerance ($CMOD_c$) than Portland cement concrete.
Verifies the chemical compatibility and stability of mineral basalt fibers ($l_f = 45\text{ mm}$, $d_f = 9\ \mu\text{m}$, $\sigma_f = 4810\text{ MPa}$) in high-alkalinity geopolymer matrices.

Evidence summary

Binder Formulation:
Geopolymer: Metakaolin-synthesized poly(siloxo-sialate) (PSS, $[\text{Si-O-Al-O-Si-O}]_n$).
Control: High early strength Portland cement (CPV ARI PLUS).
Basalt Fiber Characteristics: Length $l_f = 45\text{ mm}$, diameter $d_f = 9\ \mu\text{m}$, density $2.8\text{ g/cm}^3$, tensile strength $\sigma_f = 4810\text{ MPa}$, elastic modulus $E_f = 89\text{ GPa}$, elongation 3.15 %.
Fracture Properties (Three-Point Bending Notched Beams):
Plain Matrix (0 % fiber):
- Geopolymer: $K_{Ic} = 1.34\text{ MPa}\cdot\text{m}^{1/2}$, $CMOD_c = 0.045\text{ mm}$.
- Portland cement: $K_{Ic} = 0.85\text{ MPa}\cdot\text{m}^{1/2}$, $CMOD_c = 0.028\text{ mm}$.
0.5 vol. % Basalt Fiber:
- Geopolymer: $K_{Ic} = 2.45\text{ MPa}\cdot\text{m}^{1/2}$, $CMOD_c = 0.122\text{ mm}$.
- Portland cement: $K_{Ic} = 1.48\text{ MPa}\cdot\text{m}^{1/2}$, $CMOD_c = 0.065\text{ mm}$.
1.0 vol. % Basalt Fiber:
- Geopolymer: $K_{Ic} = 3.68\text{ MPa}\cdot\text{m}^{1/2}$, $CMOD_c = 0.185\text{ mm}$.
- Portland cement: $K_{Ic} = 2.15\text{ MPa}\cdot\text{m}^{1/2}$, $CMOD_c = 0.110\text{ mm}$.

Linked Atlas nodes

02_concepts/matrix_fracture_toughness.md
02_concepts/interface_properties.md
04_material_systems/geopolymer_ecc.md
02_concepts/matrix_fracture_toughness.md

Relationship to Victor Li book

Relates to Victor Li (2019) Chapter 2 (Matrix Fracture Toughness $K_m$) and Chapter 7 (Alternative Mineral Fibers).
Demonstrates that geopolymer concrete exhibits higher uncracked matrix fracture toughness ($K_{Ic}$) than Portland concrete, highlighting that for pseudo strain-hardening (PSH) in geopolymer ECC, matrix toughness must be controlled by excluding coarse aggregate and adjusting Si/Al ratios.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`02_concepts/matrix_fracture_toughness.md`	Metakaolin-based geopolymer concrete exhibits higher intrinsic Mode I fracture toughness ($K_{Ic} = 1.34\text{ MPa}\cdot\text{m}^{1/2}$) than Portland concrete ($0.85\text{ MPa}\cdot\text{m}^{1/2}$)	Three-point bending tests on notched beam specimens ($150 \times 150 \times 500\text{ mm}$)	Section 4 & 5, Fig. 3, Table 3	verified_from_pdf
`04_material_systems/geopolymer_ecc.md`	Basalt fibers (1.0 vol. %) increase the critical stress intensity factor of geopolymer concrete by 174 % (to 3.68 MPa·m^{1/2})	Notched beam fracture testing demonstrated superior fiber bridging and chemical resistance of basalt fibers	Section 5, Fig. 3 & 4, Table 3	verified_from_pdf

Verification status

PDF preserved: yes (dias-2005-fracture-toughness-of-geopolymeric-concretes.pdf)
Text extracted: yes (full_text/dias-2005-fracture-toughness-of-geopolymeric-concretes_full_text.md)
DOI verified: yes (10.1016/j.cemconcomp.2004.02.044)
Metadata verified: yes (Cement & Concrete Composites, Vol. 27, No. 1, pp. 49–54, 2005)
Claim-evidence matrix ready: yes

Cautions

Concretes contained coarse aggregates and high $w/b$ ratios, resulting in high matrix fracture toughness ($K_{Ic} > 1.3\text{ MPa}\cdot\text{m}^{1/2}$), which yields deflection-hardening rather than direct tensile pseudo strain-hardening.
Long basalt fibers ($l_f = 45\text{ mm}$) require careful mixing to prevent fiber clumping.