Researchers have conducted new investigations to evaluate the low-temperature performance of asphalt mixtures modified with basalt fiber and rubber powder, particularly under challenging freeze-thaw conditions typical of regions experiencing large temperature fluctuations. The study, published recently, provides insights on how these modified asphalt mixtures can perform more effectively, enhancing pavement durability during harsh winter months.
The focus of the research was on basalt fiber-rubber powder composite modified asphalt mixtures (BRMAM), analyzed through several mechanical property tests and with specific attention to how freeze-thaw cycles impact their performance. The objective was to understand the deterioration mechanisms and how the content of basalt fibers can reinforce asphalt under difficult environmental conditions.
Freeze-thaw damage is long-recognized as one of the most prevalent issues affecting asphalt pavements. This damage arises when water infiltrates the voids within the pavement during thawing, and then freezes, causing expansion and cracking as temperatures drop. Researchers emphasized the importance of accurately assessing the low-temperature performance of asphalt materials, particularly for applications sensitive to environmental extremes.
To carry out this study, the research team developed a series of rigorous experiments, including splitting tensile tests, three-point bending tests, and semi-circular bending tests. These methods enabled detailed assessment of how BRMAM holds up under different fiber contents, which ranged from as low as 0.1% to 1.5%. Interestingly, the findings indicated optimal fiber reinforcement occurs at approximately 0.3% fiber content, where the impact on low-temperature performance is maximized without the drawbacks seen when fibers were added excessively.
According to the results, the splitting tensile strength of BRMAM significantly decreased with increasing freeze-thaw cycles; this degradation highlights the vulnerability of asphalt mixtures to the damaging effects of repeated freezing and thawing. Notably, the study found, "the incorporation of excessive basalt fibers may lead to contrary effects, which is an important consideration for engineers."
The assessment also underscored how adding basalt fibers contributes positively to the mechanical stability of the asphalt mixtures. By forming a network structure within the pavement material, the fibers effectively improve crack resistance and reduce brittleness, enhancing overall pavement longevity. This is evident from the data showing how BRMAM with optimal fiber content exhibited the least sensitivity to freeze-thaw cycles.
One significant takeaway from the research is the recommendation for engineers to optimize the fiber content based on the specific conditions of the asphalt's environment. The study suggests, "when fibers content is between 0.2 and 0.4%, BRMAM demonstrates optimal low-temperature performance and the least sensitivity to freeze-thaw cycles." By focusing on such parameters, the performance of asphalt pavements can be significantly improved, leading to longer-lasting and more resilient infrastructures.
With data supported by rigorous experiments, this research offers valuable insights for the future of asphalt pavement management, especially in cold climates where freeze-thaw damage is inevitable. The comprehensive evaluations conducted provide technical support and recommendations for implementing these innovative materials on roads and highways, making asphalt mixtures more suitable for extreme conditions.
