Version 1: The Four Faces of Rebar: Matching Steel to Concrete Strength
Reinforcing bar, or rebar, is an essential component in reinforced concrete. These steel bars vary in properties, including appearance, load-bearing tensile strength, and cost. Ultimately, selecting the right type often boils down to balancing your budget against the expected structural loads. Here’s a quick overview of the four primary types of steel bars and their common applications.
Hot Rolled Deformed Bars
In construction, “deformation” usually isn’t a welcome word, but it’s a critical feature of hot rolled deformed steel bars. These bars are rolled while still hot, which gives them a distinct, textured surface. The ribs along their length are key; they significantly improve the bond with concrete, making them a popular choice for reinforcement. This type typically achieves a tensile strength of around 60,000 psi.
Cold Worked Steel Bars
Cold worked steel bars also boast a tensile strength of approximately 60,000 psi, but their manufacturing process differs considerably. Instead of being worked hot, these steel bars are processed at room temperature. They may be twisted or manipulated to create a ribbed texture, again enhancing their adhesion to the surrounding concrete. A major advantage of cold working is the ability to achieve extremely tight tolerances in the finished bars, particularly in terms of straightness along their entire length.
Mild Steel Plain Bars
Unlike their deformed counterparts, mild steel plain bars lack the ribbed surfaces that improve bonding with concrete. To compensate, hooks are sometimes incorporated at the ends to provide additional grip. The smooth surface of these steel bars inherently means lower strength in reinforced concrete—typically about 40,000 psi. However, they are also more affordable, making them an economical choice if the anticipated loads are unlikely to exceed this limit.
Prestressing Steel Bars
Prestressing steel bars are distinct, often comprising multiple individual steel threads. These can be as few as two or three strands, or up to six spun helically around a thicker central core strand. The cold-drawn wires collectively deliver exceptionally high tensile strength, often exceeding 250,000 psi. This remarkable strength is why prestressing steel bars are specifically chosen for reinforcing concrete structures designed to carry the heaviest loads, such as large building slabs and bridge decks. For more insights on building foundations, a solid concrete base is a prerequisite for installing a steel building frame; you can visit our blog post for a guide on how to build your own steel-framed house.