Glossary

Rebar—short for “reinforcing bar”—is steel reinforcement embedded in concrete to carry tensile forces the concrete itself can’t resist. Concrete is strong in compression but weak in tension; deformed steel bars bond to the surrounding concrete so the two materials act together, limiting cracking, increasing load capacity, and providing ductility so structures don’t fail suddenly.

Modern rebar is almost always “deformed,” meaning the bar surface has raised ribs or patterns that mechanically lock into the concrete. In North America bar sizes are #3 through #11 and larger, where the number is the nominal diameter in eighths of an inch (#4 ≈ 1/2 in, #8 ≈ 1 in). Metric systems use 10M, 15M, 20M, etc., with slightly different diameters. Common strength grades are 60 ksi yield (Grade 60) and higher grades like 75, 80, and 100 ksi for longer spans or congested areas. Typical specifications include ASTM A615 (carbon steel), A706 (low-alloy weldable), A955 (stainless), and A1035 (low-corrosion “microcomposite”/CR rebar); A706 is preferred when welding is required, while A615 generally is not welded unless procedures per AWS D1.4 are followed.

To resist corrosion, rebar may be coated or made from corrosion-resistant alloys. Epoxy-coated bars (often green) are common for bridge decks and marine exposure; hot-dip galvanized and stainless bars offer longer life at higher cost. Because coatings can reduce bond, development and splice lengths are increased compared with black bar. In very aggressive environments, nonmetallic FRP (glass- or carbon-fiber) “rebar” is also used; it doesn’t corrode but behaves differently in design.

Bars are detailed and placed to carry different actions: longitudinal reinforcement for bending, stirrups and ties for shear and confinement, and compression bars where needed. Proper concrete cover protects steel from corrosion and fire. Bars are anchored by hooks or sufficient development length, spliced by lap splices or mechanical couplers, and supported on chairs or spacers to maintain cover. Installers tie bars together with wire to hold the cage during placement, then concrete is placed and vibrated so it fully surrounds the steel.

In short, rebar is the hidden steel skeleton inside reinforced concrete. The right grade, size, spacing, cover, anchorage, and corrosion protection are what turn brittle concrete into the tough, crack-controlled, and ductile material used for buildings, bridges, pavements, tanks, and foundations.

A rebar bolt is a specialized type of steel anchor used in construction, particularly for projects involving underground rock or concrete, such as mining and tunneling. Unlike a standard bolt, it has a surface with ribs or corrugations similar to rebar, which is designed to enhance its grip and friction with the surrounding material. One end of the bolt is threaded to allow for the attachment of a nut and a bearing plate, while the other end is often angled at 45 degrees to help with installation.

The installation of a rebar bolt involves inserting it into a pre-drilled hole, where it is secured using either a fast-setting resin cartridge or a more traditional cement mortar. Once in place, the threaded end of the bolt is tightened, which tensions the bolt and presses a bearing plate against the surface. This creates a stable anchor point. Rebar bolts are an important component in various applications, including rock support, stabilizing retaining walls and slopes, and reinforcing underground mines and tunnels.