Concrete embedded with steel reinforcement bars, plates, or fibers is one of the world’s most commonplace construction materials. Reinforced concrete, as it is known, can be found in everything from massive bridges and skyscrapers to individual home foundations and the roads underneath our feet. Here’s a quick look at why this composite material is so popular, and how it’s made:
Isn’t Concrete Strong Enough? Why Does it Need Reinforcement?
While concrete is an exceptionally tough material, resistant to compression forces, it’s also rather susceptible to cracking under extreme tensile stress. This makes it vulnerable to earthquakes, heavy vibrations, and other calamities against which architects must take consideration.
How Steel Helps
Consider reinforced concrete to combine the best of both worlds: concrete itself, while strong under pressure, is weak when stretched; while steel, somewhat more flexible, withstands bending and pulling forces better. The resulting composite material retains the inexpensive, easily moldable, weather resistant, and fireproof traits of concrete while standing up much more reliably to tensile stress.
How is the Reinforcement Done?
Reinforced steel is most commonly produced by pouring liquid concrete into a mold around a steel rebar or cable skeleton. These steel rods are typically placed at points where the greatest tensile stress is anticipated, if not throughout the entire structure.
Often, construction engineers will create pre-stressed concrete, in which the concrete is poured around heavy steel bars or cables that are already under considerable tensile stress. Once the concrete is poured and hardens, static friction transfers these tensile forces directly into it as compression. Subsequent tensile stress on the concrete is transferred directly onto the reinforcing structure.
Occasionally, small fibers of steel (or even other materials like glass or synthetics) may be incorporated directly into the concrete mix – this results in a material with improved resistance to cracking over regular concrete, though perhaps with less of a strength increase than is found in rebar-embedded concrete.
Questions about rebar or steel-based reinforcement in general? Contact the metal experts at Madison Steel today.