Fiber-reinforced concrete or fibre-reinforced concrete is concrete containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers – each of which lend varying properties to the concrete. In addition, the character of fiber-reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation, and densities. 

ASTM C1550 determines the flexural toughness of fiber-reinforced concrete. Flexural toughness is the maximum stress (put) onto a specimen before it cracks or breaks. In this instance it is expressed as energy absorption in the post-crack range using a round panel supported on three symmetrically arranged pivots and subjected to a central load point.