Steel fibers and rebar are both required at times, and only in a few restricted circumstances can one successfully replace the other. Simply put, steel fibers prevent cracks while rebar restricts crack breadth. That is not possible with rebar. Example 2 is a two-mile-long concrete roadway. It must be reinforced with steel bars to prevent total collapse. Concrete that is properly designed and constructed should never require reinforcement with steel fibers or rebar. However, this isn't always the case. Occasionally, there are design flaws or site conditions that may require reinforcement. When this occurs, it is necessary to add some type of reinforcement to the concrete. Fiber-reinforced concrete (FRC) is one example of when steel fibers are used instead of rebar. FRC is a composite material used to strengthen concrete structures. It consists of long fibers embedded in a matrix of resin and water. The fibers provide tensile strength to the material in all directions, but especially in the direction of the load. This increases the resistance of the concrete to failure. Rebar is required by most building codes when constructing concrete floors. The reasons for this vary from code compliance to increased floor strength. Regardless of the reason, rebar is needed for any concrete structure over 3 inches thick. Concrete thinner than this cannot be reinforced with it because there won't be enough surface area to attach each bar.