A new study suggests that a simple combination of recycled rubber powder and nano-silica could make concrete far more resistant to damaging freeze–thaw cycles while also improving sustainability.
Study: Synergistic effect of rubber powder and nano-silica on pore structure and frost resistance of concrete. Image Credit: mailcaroline/Shutterstock.com
Published in Scientific Reports, the research examines how these two materials work together to modify the internal structure of concrete and improve its durability in cold environments.
The findings show that incorporating rubber powder and nano-silica enhances pore structure characteristics, strengthens microstructural stability, and significantly improves resistance to freeze–thaw damage. At the same time, the approach supports sustainable construction by incorporating recycled rubber materials into concrete.
Addressing Freeze-Thaw Challenges in Concrete
Concrete is widely used in construction because of its strength, durability, and versatility. However, its performance can decline in environments exposed to repeated freeze–thaw cycles. When water inside the concrete freezes and expands, it generates internal stresses that can lead to cracking, surface scaling, and gradual structural deterioration.
Because of these challenges, improving freeze–thaw durability has become an important focus in concrete research. One approach involves modifying the internal structure of concrete with additives that enhance toughness, density, and resistance to moisture penetration.
Rubber powder, typically produced from recycled tires, has attracted attention because it increases toughness and flexibility. When incorporated into concrete, rubber particles can absorb stress and improve impact resistance, allowing the material to better withstand deformation during freeze–thaw cycling.
Nano-silica works in a different but complementary way. Its extremely fine particles fill microscopic pores within the cement matrix, increasing density and reducing permeability. This refinement of the microstructure limits water penetration and strengthens the overall matrix.
Together, rubber powder and nano-silica create a balanced solution.
Rubber enhances flexibility and energy absorption, while nano-silica strengthens and densifies the matrix. Their combined use therefore offers a promising strategy for improving frost resistance while supporting sustainable construction through the reuse of waste materials such as discarded tires.
Experimental Approach: Mixture Design and Testing
To better understand these combined effects, researchers prepared a series of concrete mixtures containing different proportions of rubber powder and nano-silica. Rubber powder was added at 0 %, 5 %, 10 %, and 15 % by weight of cement, while nano-silica was included at 1 %, 3 %, and 5 %.
The rubber powder used in the study was obtained from recycled tires, while the nano-silica was produced specifically for experimental purposes.
Once the mixtures were prepared, researchers evaluated their mechanical and durability performance using standard testing methods. Compressive strength, flexural strength, and water absorption were measured to determine how the additives influenced structural properties.
To assess resistance to cold environments, the concrete specimens were subjected to repeated freeze–thaw cycles. This testing simulated real-world environmental conditions and allowed researchers to evaluate how well each mixture maintained its structural integrity over time.
In addition to these performance tests, advanced characterization techniques were used to examine the concrete’s microstructure. These included scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and X-ray diffraction (XRD). Together, these analyses provided detailed insight into pore distribution, matrix density, and the structural changes caused by the additives.
Key Findings: Performance Improvements
The results showed that the combined use of rubber powder and nano-silica produced clear improvements in freeze–thaw durability and pore structure characteristics.
Rubber powder increased the ductility and toughness of the concrete, allowing it to better absorb stress and accommodate deformation during repeated freeze–thaw cycles. However, as observed in previous studies on rubberized concrete, higher rubber contents tended to reduce compressive strength compared with conventional concrete.
Nano-silica helped address this limitation by refining the pore structure of the cement matrix. Its fine particles filled micro-voids, increased matrix density, and reduced permeability. As a result, the concrete became less susceptible to water penetration and freeze–thaw damage.
When used together, the two additives created a complementary effect. Nano-silica strengthened and densified the matrix, while rubber particles improved flexibility and energy absorption. This balance allowed the modified concrete to maintain mechanical performance while significantly improving durability.
Among the tested mixtures, the most effective formulation contained approximately 5 % rubber powder and 3 % nano-silica. This mixture achieved the best balance between mechanical strength and frost resistance.
Freeze–thaw testing showed that the optimized mixture experienced significantly lower mass loss and less structural damage than conventional concrete. SEM observations revealed a denser matrix with fewer voids, while rubber particles acted as flexible inclusions that helped limit crack propagation during freeze–thaw cycles.
Further pore structure analysis indicated a reduction in harmful pores and a shift toward smaller, less damaging pore sizes. Improvements in air-void distribution also helped relieve internal stresses generated during freezing.
Applications: Advancing Sustainable Construction
These findings have important implications for the construction industry, particularly in regions where infrastructure is regularly exposed to freeze–thaw conditions.
Concrete modified with rubber powder and nano-silica could improve the durability of roads, bridges, pavements, and other transportation infrastructure that must withstand harsh winter environments. Enhanced resistance to frost damage can extend service life and reduce maintenance demands.
The material may also benefit structural components in residential and commercial buildings located in colder climates. Improved toughness and durability could contribute to more resilient building systems while lowering long-term repair costs.
Equally important are the environmental benefits. The incorporation of recycled rubber powder helps reduce waste from discarded tires and supports circular economy practices in construction. By reusing existing materials while improving performance, this approach offers a practical method for producing more sustainable concrete.
Conclusion and Future Directions
Overall, the study shows that combining rubber powder and nano-silica can significantly improve the frost resistance and durability of concrete. By refining pore structure characteristics and improving the air-void system, the modified concrete is better able to withstand repeated freeze–thaw cycles while incorporating recycled materials.
Future research could focus on evaluating the long-term durability of these mixtures under a wider range of environmental conditions, as well as assessing their economic feasibility for large-scale infrastructure projects. Investigating additional additives and optimized mix designs may also help further improve performance and expand the use of sustainable materials in concrete technology.
Journal Reference
Feng, LY., & et al. (2026). Synergistic effect of rubber powder and nano-silica on pore structure and frost resistance of concrete. Sci Rep. DOI: 10.1038/s41598-026-36480-8, https://www.nature.com/articles/s41598-026-36480-8
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