Steel rebar used in concrete construction provides reinforcement in a number of different ways, depending on what type of rebar is used. While concrete can be exceedingly dense and tough, it does not do well under torque. As a result, a structure is needed inside the concrete to hold it together. Rebar serves this purpose, but is susceptible to corrosion. Different types of rebar are designed to address this problem.
Basic ordinary steel rebar is made with carbon steel. It provides an essential strength factor to the concrete formed around it. This type of rebar is quick to rust when exposed to moisture. As moisture pervades concrete because it is porous, the rebar expands with corrosion, which eventually causes cracks in the cement. This begins the process of deterioration over time.
Rebar manufactured in Europe previously used mild steel -- made of carbon, silicon, manganese and other elements -- but today its product matches that of the United States, being twice as strong as historical rebar. Added features provide increased flexibility in the steel used today, giving it a greater chance of holding together and surviving earthquake shock waves.
Stainless Steel Rebar
Production of stainless steel rebar avoids the problem of corrosion in construction. Because the fabrication of stainless steel includes chromium, it tends to be corrosion-proof as long as the general surface of the steel is not broken. If corrosion gets inside the stainless seal, then it begins to break apart the steel with oxidation. Regardless of this factor, stainless steel rebar lasts much longer than traditional steel, which makes it a great reinforcement product for large building construction, roadways, bridges and cement structures exposed to the sea.
Similar to the processes used to create galvanized nails, galvanized steel rebar undergoes a treatment to avoid corrosion when exposed to moisture and air. This type of rebar, typically fabricated with a zinc outer surface, does not corrode as easily as basic steel does. Galvanized rebar lasts a long time, regardless of the moisture that penetrates the concrete.
As the name implies, manufacturers produce this type of rebar with a chemically-dipped coat over the entire steel surface. The epoxy creates a barrier that stops oxidation from occurring. Even if there is a break in the seal, the oxidation only occurs where the break happens, not over the entire rebar. When compared with uncoated rebar, the epoxy version lasted significantly longer without sacrificing integrity. Uses of this type of rebar include critical construction that must retain shape and structure for decades. Highway bridges are a common example.