Altwair et al. (2012) — Flexural Performance of Green Engineered Cementitious Composites Containing High Volume of Palm Oil Fuel Ash

Citation

Altwair, N. M., Megat Johari, M. A., & Saiyid Hashim, S. F. (2012). Flexural performance of green engineered cementitious composites containing high volume of palm oil fuel ash. Construction and Building Materials, 37, 518–525.

DOI: 10.1016/j.conbuildmat.2012.08.003
Atlas layer: extension
Related Victor Li book chapter: Chapter 9: Green ECC (High-Volume Industrial/Agricultural Waste SCMs) & Chapter 5: Mechanical Properties of ECC (Flexural Response and Deflection-Hardening)
Source PDF: altwair-2012-flexural-performance-of-green-engineered-cementitious.pdf
Extracted text: full_text/altwair-2012-flexural-performance-of-green-engineered-cementitious_full_text.md
Source note: source_notes/altwair-2012-flexural-performance-of-green-engineered-cementitious_source_note.md

Why this paper matters

Demonstrates the effective utilization of Palm Oil Fuel Ash (POFA)—a major agricultural waste by-product in Southeast Asia—as a high-volume supplementary cementitious material (up to POFA/cement mass ratio of 1.2, ~55 % replacement) in PVA-ECC, enhancing flexural deflection ductility and micro-crack refinement.

Main contribution

Formulates green ECC using treated/ground POFA (heated at 450 °C to remove unburned carbon, median particle size $\approx 2.99\ \mu\text{m}$, Blaine fineness $620\text{ m}^2/\text{kg}$) with 2.0 vol. % oiled PVA fibers (Kuraray REC15).
Evaluates flexural deflection-hardening across three $w/b$ ratios (0.33, 0.36, 0.38) and four POFA/C ratios (0, 0.4, 0.8, 1.2) at 3, 28, and 90 days.
Finds that while high POFA content moderately reduces first-crack strength and compressive strength (from ~55 MPa down to 25–38 MPa), it significantly boosts flexural deflection capacity (up to 13–15 mm over a 300 mm span) and refines crack patterns.
Demonstrates micro-crack width suppression: average crack width decreases from ~90 $\mu\text{m}$ in control ECC to < 45 $\mu\text{m}$ with high POFA content, with crack count increasing threefold.

Evidence summary

Material Formulation: Type I cement, treated POFA (POFA/C = 0.0, 0.4, 0.8, 1.2), silica sand ($d_{max} = 200\ \mu\text{m}$, S/C = 0.8), 2.0 vol. % oiled PVA fiber ($l_f = 8\text{ mm}$, $d_f = 40\ \mu\text{m}$, $\sigma_f = 1600\text{ MPa}$, 1.2 wt% oil coating).
Flexural Performance (4-Point Bending, 350 × 100 × 25 mm beam, span 300 mm):
Flexural deflection capacity at peak load: increases from ~5.2 mm (control) to 12.8–15.1 mm (POFA/C = 1.2) at 28 days.
Modulus of Rupture (MOR / Flexural strength): 8.5–12.5 MPa depending on $w/b$ and POFA level.
First-cracking flexural strength: 4.5–7.0 MPa.
Compressive Strength: 28-day $f_c = 25.4\text{--}54.8\text{ MPa}$ across mixes.
Crack Width & Spacing: Crack count increases from ~8–10 in control to 25–32 in POFA mixtures; average crack width stays tightly controlled below 50 $\mu\text{m}$.

Linked Atlas nodes

02_concepts/crack_width_control.md
04_material_systems/green_ecc.md
04_material_systems/pva_ecc.md
05_experiments/flexural_testing.md
06_sustainability/agricultural_waste_scms.md

Relationship to Victor Li book

Extends Victor Li (2019) Chapter 9 (Green ECC) by incorporating agricultural waste ash (POFA) alongside traditional fly ash/slag to reduce cement clinker factor and carbon footprint.
Reinforces Chapter 5 (Flexural Properties): high SCM substitution lowers matrix fracture toughness $K_m$ and interface chemical bond $G_d$, shifting the micromechanical balance favorably toward steady-state multiple cracking ($J_b'/J_{tip} \gg 1$) and pronounced deflection-hardening.

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`04_material_systems/green_ecc.md`	Replacing up to 55 % cement with treated palm oil fuel ash (POFA) enhances deflection-hardening and crack multiplication in PVA-ECC	Flexural deflection capacity increases from 5.2 mm to > 14 mm at 28 days with POFA/C = 1.2	Section 3.2, Fig. 5, Table 4	verified_from_pdf
`02_concepts/crack_width_control.md`	Inclusion of high-volume POFA refines crack distribution and reduces individual crack width below 50 $\mu\text{m}$	Crack count in 4-point bending increased from ~8 to 28, while average crack width dropped from ~90 $\mu\text{m}$ to 42 $\mu\text{m}$	Section 3.3, Fig. 8, Table 5	verified_from_pdf
`06_sustainability/agricultural_waste_scms.md`	Heat-treated and ball-milled POFA exhibits pozzolanic reactivity suitable for sustainable ECC without compromising ultimate ductility	POFA ground to $d_{50} \approx 3.0\ \mu\text{m}$ and heated at 450 °C achieved 28d compressive strength of 25–38 MPa with high ductility	Section 2.1 & 3.1, Fig. 1, Table 1	verified_from_pdf

Verification status

PDF preserved: yes (altwair-2012-flexural-performance-of-green-engineered-cementitious.pdf)
Text extracted: yes (full_text/altwair-2012-flexural-performance-of-green-engineered-cementitious_full_text.md)
DOI verified: yes (10.1016/j.conbuildmat.2012.08.003)
Metadata verified: yes (CBM, Vol. 37, pp. 518–525, 2012)
Claim-evidence matrix ready: yes

Cautions

The paper primarily reports 4-point bending flexural deflection; direct uniaxial tensile strain capacity should be verified separately when evaluating pure tensile ductility.
Raw POFA contains high unburned carbon and coarse particles; thermal treatment (450 °C) and fine grinding ($< 3\ \mu\text{m}$) are mandatory to ensure pozzolanic reactivity and avoid excessive water demand.