Reduce the chance your concrete will crack from expansion and contraction and other tensile stresses. Concrete inherently stands up to high compressive loads—adding this rebar strengthens it against pulling forces as well. The rebar's surface is textured; poured concrete fills in the gaps between those ridges to create a strong bond.

Fiberglass rods are best for concrete that's exposed to water, salt water, and chemicals. They resist corrosion when those substances seep through the concrete, extending your concrete’s life. Compared to carbon steel rebar, these handle higher loads since they have higher tensile strength, yet they’re about 75% lighter in weight. However, unlike carbon steel, you can’t form these rods onsite; you must shape them beforehand.