How to Choose Between Metallic and Non-Metallic Fibers When Selecting Fibers for UHPC?

In fiber selection for UHPC, "how to choose between metallic fibers (mainly steel fibers) and non-metallic fibers (such as polyvinyl alcohol PVA fibers, basalt fibers, etc.)" is a key technical decision point. This choice directly affects UHPC's final mechanical properties, durability, application scenarios, and even cost. The strategy Qinglong Group has developed in practice is: prioritize steel fibers to meet the vast majority of structural and high-performance decorative applications; under specific corrosion-resistance or non-magnetic requirements, carefully evaluate and select high-performance non-metallic fibers.

Steel fiber is currently the most mainstream and technically mature choice in UHPC applications. Its core advantages lie in its high elastic modulus (approximately 200 GPa) and thermal expansion coefficient close to that of the cement matrix, which ensures the fibers can effectively transfer stress and inhibit crack propagation, thereby significantly improving UHPC's flexural strength, toughness, and impact resistance. Hooked-end steel fibers provide excellent mechanical anchorage. Qinglong uses high-performance copper-plated steel fibers in the vast majority of architectural curtain walls and structural components; these fibers offer sufficient stability in alkaline environments and meet durability requirements over the design service life of building structures.

Non-metallic fibers, such as high-modulus PVA fibers or basalt fibers, are mainly used in extremely harsh corrosive environments or in projects with special requirements for non-magnetic and insulating properties. For example, PVA fibers have strong alkali resistance and theoretically offer better corrosion resistance in marine chloride environments or in bridge projects subject to severe de-icing salt attack. However, the elastic modulus of non-metallic fibers is typically lower than that of steel fibers (e.g., PVA fibers at approximately 40 GPa), and their bond performance with the cement matrix also needs to be optimized through surface treatment, which may result in slightly lower ultimate tensile strength and toughness peaks in UHPC compared with UHPC reinforced with high-quality steel fibers.

Therefore, the key to making this choice lies in precisely matching project requirements. Qinglong's technical team comprehensively evaluates the project's mechanical performance requirements, exposure environment, long-term durability goals, and cost budget. For the vast majority of architectural applications, cost-effective and reliable steel fibers are the first choice. Only when corrosion risk is clearly identified as the controlling factor, and a possible partial reduction in mechanical performance is acceptable, will non-metallic fiber solutions be studied in depth. Qinglong has accumulated R&D results and data on UHPC with different fibers, enabling it to provide customers with optimal fiber selection recommendations based on specific operating conditions.