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

Selecting fibers for UHPC requires consideration of project requirements, service environment, and cost budget. Metallic fibers (steel fibers) and non-metallic fibers (alkali-resistant glass fibers, PVA fibers) each have their strengths and weaknesses. Based on extensive project practice, Qinglong has summarized a clear decision-making logic and matching scenarios.

I. Metallic Fibers (Steel Fibers): The Preferred Choice for High Strength and Impact Resistance

The core advantages of steel fibers lie in mechanical performance, making them suitable for load-bearing and harsh environments. Performance characteristics: tensile strength ≥2000MPa, excellent impact resistance, able to increase UHPC flexural strength by 50%-80%, extend crack propagation paths, and avoid brittle fracture; Applicable scenarios: projects with high strength and impact resistance requirements such as bridge components, industrial flooring, and blast-resistant structures. Qinglong used steel fibers in the UHPC pavement layer of a municipal bridge, achieving a flexural strength of 25MPa and withstanding repeated rolling by heavy vehicles; Disadvantages and precautions: high density (approximately 7.8g/cm³), which increases the self-weight of UHPC; prone to rusting (stainless steel fibers or anti-corrosion treatment are required); relatively high cost (about 3-5 times that of glass fibers). Qinglong's stainless steel fiber UHPC formulation has been used in coastal projects for 5 years without any rusting.

II. Non-Metallic Fibers: The Suitable Choice for Lightweight and Corrosion Resistance

Non-metallic fibers are mainly alkali-resistant glass fibers and PVA fibers, suitable for decorative and conventional scenarios. Performance characteristics: alkali-resistant glass fiber has a tensile strength ≥1500MPa and a density of 2.6g/cm³, is lightweight and eco-friendly, with strong corrosion resistance and no rusting; PVA fiber has good flexibility and outstanding crack resistance, but slightly weaker high-temperature resistance; Applicable scenarios: non-load-bearing or secondary load-bearing structures such as building curtain walls, decorative components, and landscape sculptures. Both the light-transmitting UHPC components of the Century Plaza on Nanjing East Road at Shanghai New World and the exterior wall panels of the Shenzhen Yirui Biotechnology Building by Qinglong use alkali-resistant glass fibers, ensuring both design flexibility and decorative requirements; Disadvantages and precautions: impact resistance is lower than that of steel fibers, and performance declines under long-term high temperature (>200℃) environments. Qinglong compensates for the insufficient impact resistance by optimizing fiber content (2.5%-3%), ensuring safe use in conventional scenarios.

III. Core Decision-Making Logic: Match by Need, Balance Performance and Cost

The decision should revolve around three core dimensions. Performance requirements: choose steel fibers for load-bearing and impact resistance; choose non-metallic fibers for decoration, lightweight needs, and corrosion resistance; Environmental conditions: choose alkali-resistant glass fibers (or stainless steel fibers) for coastal and high-humidity environments, while PVA fibers can be chosen for dry indoor settings; Cost budget: cost-sensitive projects should prioritize alkali-resistant glass fibers, while high-performance projects can accept the cost premium of steel fibers; Qinglong's customized solutions: support for recommending fiber types based on project parameters (such as load, environment, and design), even hybrid fiber formulations (steel fiber + glass fiber) that combine strength and lightness. A high-end commercial complex project adopted hybrid fibers to achieve the optimal balance between performance and cost.