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In this topic we are going to cover one of the most important ingredients in UHPC mix – high strength steel fibers.

UHPC – Ultra High-Performance Concrete is a type of new generation concrete that allows to design and produce complex forms of great resistance and, at the same time, very light and slender. It has a high resistance to compression, bending and wear, as well as high durability compared to High Performance and normal concretes. It’s a concrete of fluid / liquid consistency that achieves extremely low water absorption and high resistance to penetration of chloride ions. It is manufactured with polymeric, inorganic or metallic fibers and silicon aggregates.

Steel fibers in UHPC are relevant when increasing ductility and greater capacity to energy absorption that results in less damage. They are defined as elements of short length and small section that are incorporated into the mass of the concrete in order to achieve certain specific properties such as cracking control, increased resistance to fire, abrasion, impact and others.

For UHPC, we recommend the following SPAJIC fibers:

  • SPAJIC Microfibers SA/M 0,17x6mm
  • SPAJIC Microfibers SA/M 0,17x10mm
  • SPAJIC Microfibers SA/M 0,20×12,5mm

UHPC is formulated by combining cement, supplementary materials, reactive powders, limestone and/or quartz flour, fine sand, high-range water reducers, and water. Fiber type mostly used include high carbon steel.

Here are some of the advantages of UHPC:

  • outstanding mechanical properties
  • up to 400 times more durable material against corrosion,
  • abrasion and better impact than ordinary concrete
  • UHPC is highly resistant against acid waters, mechanical
  • abrasion and erosion
  • extremely low permeability
  • ultra high-strength, ductile material
  • design flexibility, improved aesthetics
  • random distribution throughout concrete mix
  • longer life span of structures
  • exhibit exceptional energy absorption, capacity and resistance to
  • fragmentation ideal material to perform under explosive
  • blast resistance panels

Thank you for reading!

Share your experience/comments below.

Best regards,


4 thoughts on “Steel fiber solution for UHPC

  1. Interesting!
    Have you given up on using better a better produced concrete solution with cement only as binder? Cant we can still use ordinary concrete with steel fiber? I think we need to handle it from mixing to transport and cast it under better control than today.
    Best regards
    Yngve Alvarsson

    1. Dear Yngve,

      Steel fiber have been continuously used in normal concrete for decades and will continue to be used in different applications (industrial floors, external pavements, shotcreting, precast ..etc)
      UHPC is completely new class of concrete developed in early ‘90 which provides superior mechanical and durability properties compared to normal and High Performance Concretes.

      Best regards!

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