In reinforced concrete, which material is often added to increase strength?

In reinforced concrete, adding steel rods and wire is a common practice to significantly increase the material's strength and durability. This method is based on the principle that concrete is strong in compression but weak in tension. Steel, on the other hand, exhibits high tensile strength. By integrating steel rods (also known as rebar) and wire mesh into the concrete mix, the composite material can withstand both compressive and tensile forces, making it much more resilient under various loads and conditions.

This combination of materials allows for the construction of structural elements such as beams, columns, and slabs that can endure the stresses from weight, loads, and environmental factors. The interaction between the concrete and steel ensures that as the concrete expands or contracts due to temperature changes, the steel provides the necessary support to prevent cracking or failure.

The other materials listed do not serve the same purpose in reinforcing concrete. Wood fibers, for instance, could add some properties but would not provide the tensile strength needed for structural integrity. Hollow bricks and clay tiles are typically used as building materials themselves rather than as reinforcing agents and do not enhance the strength of concrete in the way that steel does.