When and Where to Add Steel Reinforcing Rods

Appropriate use will make your structure stronger

By Robert Ferguson

Photo by iStockphoto.com

Steel reinforcing rods, commonly referred to as rebar, are used to reinforce poured concrete and masonry structures. Around the globe rebar -- or steel reinforcing rods -- are used widely in building applications. Without rebar, many of today's concrete structures would not be possible, which underscores the importance of these important structural tools. But the use of rebar can't be done randomly. There is a logic and order to their application that you should understand before using rebar for your project.

History

The first structures built using rebar to reinforce concrete where built in the late 1800s by a building contractor named Francois Coignet. Early types of rebar were made of iron. Many of these structures are still standing today. The first rebar structure built in the United States was the Pacific Coast Borax Company's refinery in 1893 by Francis Marion Smith.

Types

Tempered steel is the most common material used to fabricate rebar. The rebar is rust-resistant because of the lack of oxygen and pH levels once it is encased in concrete. Epoxy-coated, galvanized and stainless-steel are materials employed in areas where reinforced concrete is exposed to salt such as coastal areas and road de-icing in the winter. Common thicknesses found in most construction projects is No. 3 rebar, which is 10mm or 3/8 inches, and No. 4 rebar, which is 12mm or 1/2 inches thick. During rebar manufacturing, ridges or ribs are incorporated into the design to give it added anchoring strength in the concrete.

Uses

Not all concrete construction requires the addition of rebar. Sidewalks, some driveways and small slabs may not require rebar. Use rebar in foundation footings, foundation walls and columns. Larger driveways will benefit from the addition of rebar. Use rebar to reinforce block walls during construction of homes to add additional strength to the structure.

Welding

Installing mechanical couplers, wiring and in some cases welding are practices used to hold the reinforced steel together. Welding rebar requires obtaining an invoice from the manufacturing mill stating the rebar is suitable for welding. Large projects employ rod busters to fabricate rebar cages on or off the construction site using hydraulic benders and shears. For smaller projects, workers use a device called a Hickey to bend the rebar by hand where applicable.

Safety

Due to the dangers associated with impalement, steel reinforced plates are installed on the on the ends of exposed rebar before it is encased in concrete. Another safety measure used by construction workers is to install plastic mushroom caps on the protruding ends of the rebar. The caps are effective against cuts and scratches but offer little protection from serious injury.

Benefits

Without the benefits of reinforced steel in concrete, projects built on soft or unstable ground, columns, archways and many other applications in concrete and masonry construction would be impossible.