Do basalt fibers corrode in highly alkaline environments?
Topic(s) : Material science
Co-authors :
Susana GARCIA-MAYO (BELGIUM), Hubert RAHIER , David SEVENO (BELGIUM)Abstract :
The construction sector, a highly impactful industry, is shifting towards sustainable practices that align with global sustainability objectives, focusing on reducing CO2 emissions and resource use. Textile reinforced cements (TRC) emerge as a promising alternative, reducing material usage and weight compared to traditional construction materials like steel-reinforced concrete. TRCs combine concrete strength with improved mechanical properties provided by textile reinforcements, strategically distributed within the matrix, increasing the load-bearing capacity of the material and its resistance to cracking and spalling. The selection of textiles plays a critical role in determining the final properties of the composite.
The use of basalt fiber textiles, as an alternative to glass fibers, contributes to preserving structural integrity at elevated temperatures due to the basalt’s ability to maintain its mechanical properties even under extreme conditions. The corrosion resistance of basalt fibers is crucial in aggressive environments where steel corrosion could compromise conventional concrete. However, the corrosion resistance of basalt fibers in alkaline environments, such as those present in concrete, remains a topic of ongoing research and debate. While certain studies suggest remarkable resistance of basalt fibers to corrosion, others indicate potential changes in the fiber structure when exposed to highly alkaline conditions.
These divergences highlight the need for a more comprehensive and standardized approach. Our research investigates the corrosion processes affecting various basalt fibers having diverse commercial sizings. Our primary objective is to identify trends that can predict the long-term performance of basalt fiber textiles in concrete, linking their surface physico-chemical properties and their resistance to highly alkali environments. To achieve this, we have combined physico-chemical characterization including composition analysis through XRF and XRD, surface chemistry assessment via XPS, and surface topography using SEM (Figure 1). Additionally, we investigated wettability at the fiber scale through contact angle measurements, combined with mechanical analyses, including single fiber tensile and pull-out tests. In the majority of the samples, we observed either a reduction in the contact angle or a significant decrease in diameter after exposing the fibers to a highly alkaline environment, indicating an ongoing corrosion process. However, this effect is absent in some samples, where there is neither variation in contact angle nor in diameter. This suggests that the sizing might be serving as a protective layer in those cases. Developing a comprehensive understanding of the surface properties of basalt fibers, the influence of the chemical composition and the impact of the different parameters in the corrosion process represents an initial key step in optimizing their use as reinforcement for cementitious matrices.
The use of basalt fiber textiles, as an alternative to glass fibers, contributes to preserving structural integrity at elevated temperatures due to the basalt’s ability to maintain its mechanical properties even under extreme conditions. The corrosion resistance of basalt fibers is crucial in aggressive environments where steel corrosion could compromise conventional concrete. However, the corrosion resistance of basalt fibers in alkaline environments, such as those present in concrete, remains a topic of ongoing research and debate. While certain studies suggest remarkable resistance of basalt fibers to corrosion, others indicate potential changes in the fiber structure when exposed to highly alkaline conditions.
These divergences highlight the need for a more comprehensive and standardized approach. Our research investigates the corrosion processes affecting various basalt fibers having diverse commercial sizings. Our primary objective is to identify trends that can predict the long-term performance of basalt fiber textiles in concrete, linking their surface physico-chemical properties and their resistance to highly alkali environments. To achieve this, we have combined physico-chemical characterization including composition analysis through XRF and XRD, surface chemistry assessment via XPS, and surface topography using SEM (Figure 1). Additionally, we investigated wettability at the fiber scale through contact angle measurements, combined with mechanical analyses, including single fiber tensile and pull-out tests. In the majority of the samples, we observed either a reduction in the contact angle or a significant decrease in diameter after exposing the fibers to a highly alkaline environment, indicating an ongoing corrosion process. However, this effect is absent in some samples, where there is neither variation in contact angle nor in diameter. This suggests that the sizing might be serving as a protective layer in those cases. Developing a comprehensive understanding of the surface properties of basalt fibers, the influence of the chemical composition and the impact of the different parameters in the corrosion process represents an initial key step in optimizing their use as reinforcement for cementitious matrices.