If you’ve been in the design and construction world for a while, you’ve probably heard horror stories about fiber reinforced concrete (FRC): that it doesn’t finish well with a trowel, it dries too fast, or the fibers ball up instead of distributing evenly through the mix.
These complaints aren’t baseless; they can and do happen. In fact, our first experience with FRC nearly ended in disaster. It seemed that everything that we were told could go wrong did go wrong. But we quickly understood why: the project team lacked sufficient real-world FRC experience.
This lesson stuck with us here at Forté Structural Engineering. Since then, in the right applications and with a knowledgeable team, we’ve seen FRC deliver results that traditional concrete simply can’t.
Here’s a more balanced view than you’ll typically get about the pros and cons of FRC:
A Strong Option in the Right Situation
Traditional rebar has long been the standard in pavements and slabs-on-grade, but adding fibers to the mix can improve performance and efficiency in some situations. FRC isn’t a magic bullet—it isn’t right for every project—but when used correctly, with the right mix, product, and application, it can deliver real benefits to owners, engineers, and builders. Here are some areas where FRC can shine:
- Replacement of temperature and shrinkage reinforcing in slabs and pavements
- Faster schedules by reducing or eliminating rebar placement
- Crack control that minimizes long-term maintenance
- Extended joint spacing—potentially up to four times greater than with conventional reinforcing
- Integral reinforcement is distributed throughout the slab
- Improved durability with increased corrosion resistance (synthetic fibers don’t rust)
For applications such as slab-on-grade work and other large surface projects where cracking and joint spacing are critical concerns, these benefits can be significant.
Where FRC Can Go Wrong
FRC is not a cure-all. It doesn’t replace rebar in structural elements, like beams and columns. Poor mix designs or placement techniques can cause serious problems. Finishing suffers if the mix isn’t adjusted for the fiber content. Common issues like balling of fibers or rough surfaces are real, but preventable with the right fiber type and dosage, slump adjustments, and experienced crews.
There are multiple fiber types (and many products) aimed at different performance goals, and choosing the wrong one for the application is a common root cause of the horror stories. That’s why it’s so important to understand the differences among products and to match the right fiber to the right job. Preconstruction coordination with the supplier and clear finishing expectations also go a long way.
As a result, when FRC is used on the right project and executed by an experienced team, it can outperform conventional concrete in speed, cost, quality and longevity.
