Concrete Reinforcement
Introduction
Concrete is incredibly strong in compression, but weak in tension. As a result, tension strength needs to be added to the concrete regardless of where the concrete is being used. This is typically done with steel bars or chords of some kind, as they excel in tension.
There are two main types of reinforcing steel for cast-in-place concrete; deformed bars and welded wire fabric.
Reinforcing Bars (Rebar) Chart
Size
Available in diameters ⅜” to 2 ¼”. Bars are designated by numbers that represent the ⅛” increment in nominal diameter of the bar.
| Number | Size (Diameter) | Number | Size (Diameter) | Number | Size (Diameter) |
| 9 | 9/8” or 1-⅛” | 17 | 17/8” or 2-⅛” | ||
| 10 | 10/8” or 1-¼” | 18 | 18/8” or 2-¼” | ||
| 3 | ⅜” | 11 | 11/8” or 1-⅜” | ||
| 4 | 4/8” or ½” | 12 | 12/8” or 1-½” | ||
| 5 | ⅝” | 13 | 13/8” or 1-⅝” | ||
| 6 | 6/8” or ¾” | 14 | 14/8” or 1-¾” | ||
| 7 | ⅞” | 15 | 15/8” or 1-⅞” | ||
| 8 | 8/8” or 1” | 16 | 16/8” or 2” |
Bonding
Reinforcing steel and concrete must be bonded together to provide maximum strength and benefits from the reinforcement. For this reason rebar is given a unique shape and texture that allows it to be ‘grabbed’ easier.
There are several different ways to do this, but essentially they all involve ribbing the rebar to produce friction and valleys that increase surface area.