Researchers have found that shredded composites from recycled wind turbine blades can significantly improve the mechanical performance of cement-based mortars—highlighting a promising use for a growing stream of industrial waste.
Study: Sustainable cement-based mortar with shredded material recycled from end-of-life wind turbine blades. Image Credit: WINDCOLORS/Shutterstock.com
In a recent study published in Scientific Reports, the team explored this potential by incorporating shredded composite (SC) material from end-of-life (EoL) wind turbine blades (WTBs) into mortar mixtures. Their aim was to evaluate whether these recycled fibers could serve as partial replacements for either cement or aggregate. Using mechanical testing, digital image correlation (DIC), and microstructural analysis, the researchers assessed the performance of two SC size fractions—0–2 mm and 0–32 mm—across various mix designs.
Background
As wind turbines reach the end of their service lives, disposing of their composite blades made from tough, fiber-reinforced polymers has become a growing environmental concern. At the same time, the construction industry is actively seeking alternatives to conventional concrete materials to reduce its environmental impact. These two trends are converging in research efforts that explore how decommissioned WTBs might be reused in cementitious materials.
Previous studies have tested various forms of WTB recyclate in concrete applications, including chopped blade segments used as aggregate, powdered materials as cement replacements, and fibrous additions to enhance tensile strength. While these approaches have shown promise in improving overall mechanical properties, they often overlook how such materials influence the behavior of cracks and the internal structure of the composite.
To address this gap, the current study looked specifically at how different sizes and dosages of shredded WTB material affect not just strength, but also microstructure and fracture mechanisms in mortar.
Methods
The researchers created mortar mixes using cement, water, and sand, modifying the formulations by partially replacing either the cement or aggregate with SC recovered from WTBs. Two distinct SC fractions were tested:
- Fraction I (0–2 mm): Fine particles composed of epoxy resin and micro glass fibers, used to replace 10 %, 15 %, and 20 % of the cement volume.
- Fraction II (0–32 mm): Coarser particles with longer fibers and resin, used to replace 20 %, 30 %, and 40 % of the aggregate volume.
Seven mortar mixes were prepared: one control and six experimental mixes incorporating different SC proportions. From each mix, three mortar beams (40 × 40 × 160 mm) were cast and cured for 28 days in water at 20 ± 2?°C.
To analyze performance, the team used scanning electron microscopy (SEM) and digital microscopy to assess porosity and fiber dispersion. Density was measured volumetrically, and mechanical strength was evaluated through a standard three-point bending test.
Results and Discussion
The results revealed a clear difference in performance depending on the type and role of the SC material in the mix.
When Fraction II was used to replace aggregate, the mortars showed a notable improvement in both strength and toughness. This coarser fraction helped fill intergranular voids and introduced a fiber-bridging mechanism that contributed to crack resistance. In the M.II.30 mix, the researchers observed:
- A 6.51 % reduction in density
- A 23.22 % decrease in porosity
- A 36.51 % increase in flexural strength
- An 18.09 % boost in compressive strength
Even more striking was the performance of the M.II.40 mix, which demonstrated a 248.11 % increase in toughness index compared to the control. This improvement underscores the ability of long fibers to absorb energy and delay crack propagation, which is key for structural durability under dynamic loads.
In contrast, Fraction I, used as a cement substitute, had a more mixed impact. As the proportion of fine SC particles increased, so did porosity—leading to a decline in mechanical performance. In the M.I.20 mix, results showed:
- A 27.55 % increase in porosity
- A 6.60 % reduction in density
- A 45.12 % drop in compressive strength
- A 31.48 % decrease in flexural strength
- A 44.64 % reduction in toughness
These findings suggest that while fine SC particles may offer environmental advantages, they contribute less to structural performance—likely due to limited bonding with the cement matrix and the increased void space they introduce.
Conclusion and Future Prospects
This study adds to a growing body of research suggesting that end-of-life wind turbine blades can be repurposed effectively in cementitious materials, particularly when used as aggregate replacement with longer fiber fractions. The coarser SC not only enhanced mechanical strength and toughness but also improved energy absorption, making it well-suited for use in applications like prefabricated structural elements and pavement systems.
However, not all recycled fiber forms are equally effective. The lower performance of the fine SC fraction highlights the need for further optimization, potentially through surface treatments or improved dispersion methods that enhance the interaction between the particles and the cement matrix.
Looking ahead, future research should focus on long-term durability under real-world conditions, including freeze-thaw cycles, chloride ingress, and carbonation. Understanding how these materials perform over time will be key to advancing their use in circular, low-carbon construction.
Journal Reference
Rucka, M., & Kurpinska. M. (2025). Sustainable cement-based mortar with shredded material recycled from end-of-life wind turbine blades. Scientific Reports, 15(1). DOI: 10.1038/s41598-025-15364-3. https://www.nature.com/articles/s41598-025-15364-3
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