Reinforcing steel is a material used to strengthen concrete. Woven into a maze and placed inside of forms or suspended to allow the reinforcing steel to lie in the center of a poured slab, the iron rod gives added strength to the already strong cement. Commonly called by the slang name "re-bar," the steel has a surface of raised lines and patterns to allow it to stick tightly inside of the poured concrete. Many times, the reinforcing steel is woven into a multi-layered mat to give an inner strength otherwise unobtainable to concrete or cement work.
Made of low-grade iron, this steel is not very difficult to bend. This allows iron workers to shape the long rods into horseshoe-like configurations to reinforce cement pillars. The long sections of iron rod are typically tied together with small-diameter wire and set at critical depths within the cement forms to allow the cement to flow both over and under the steel re-bar. By placing bends in the bar, it is locked into the cured cement and unable to shift position. This method of reinforcing the concrete will actually allow the concrete to bend slightly under pressure without cracking before it returns back to its original shape.
Iron workers commonly create intricate skeletal structures out of the reinforcing steel when it is to be used inside of concrete pillars or bridge pilings. Once the iron structure is complete, a wooden or steel form is placed around it prior to the cement being pumped in around it. Large vibrating rods are plunged deep inside of the reinforcing steel-lined concrete to vibrate any air bubbles out and fill in any voids. This creates a very solid piece of cement that will not have any potentially weak areas inside. Flat metal straps are often used to center the skeleton inside of the forms so it can be easily cut and removed when the form is to be taken off the cement.
Often, the re-bar will be treated with a chemical or paint to help in the prevention of rust and corrosion. The treated iron will survive much longer inside of the concrete and will not eventually rust away, leaving voids and holes inside of the cement that may weaken it. When removing reinforced concrete, the reinforcing steel is commonly cut with acetylene torches after the concrete has been broken up by a jack hammer. This allows workers to cut the material into easily managed sizes for disposal.