The Top 5 Fiber-Reinforced Concrete FAQs

Apr 29, 2024 | News

As the use of fiber-reinforced concrete (FRC) continues to expand across various concrete applications, questions arise about its benefits, application methods, and impact on concrete properties. Here, we address the top five frequently asked questions regarding fiber-reinforced concrete:

• 1 | How does fiber use impact slump or air content of concrete?

  The type, dosage, and mix design of fibers influence the slump, or flow, of concrete. However, when combined with proper admixture use, fiber-reinforced concrete can be mixed and placed with the same consistency as normal concrete. Typically, air content remains unaffected by fiber use unless additional water is added to adjust slump.

• 2 | Are steel fibers and synthetic fibers used in the same applications?

  Micro-synthetic fibers are primarily used for controlling plastic shrinkage cracks at low dosages. In contrast, steel fibers and macro-synthetic fibers are employed at higher volumes and can replace temperature and shrinkage reinforcement in similar applications, including limited structural use.

• 3 | How can fiber balling and other mixing problems be eliminated?

  Most commercially available fiber types can be successfully mixed and placed in concrete with the correct mix design and recommended fiber addition methods. Following manufacturer instructions ensures proper dispersion and minimizes mixing issues.

• 4 | What are the common issues and remedies for pumping and finishing FRC?

   Fiber-reinforced concrete can be pumped and finished effectively with a proper mix design and precautions to avoid over-finishing. While fibers may be visible on the surface, selecting appropriate techniques and fibers can achieve finished surfaces resembling plain concrete.

• 5 | Can floor joint spacing be extended with fiber use?

  Research supports extending control joint spacing in floor design when using fibers, particularly macro-synthetic and steel fibers. This is often combined with advanced concrete mix designs, chemical admixtures, and proper placement and curing practices to ensure successful results.

By Nadine Shürmann