10/07/2025
The spiral features shown in the image and highlighted by the arrows are called "helical ribs" or "transverse ribs" on a deformed reinforcing bar (commonly called a rebar).
What are these?
These are ribs or lugs formed on the surface of the rebar during manufacturing. They come in two types:
Longitudinal ribs run parallel to the bar's axis.
Transverse (or helical) ribs - run at an angle or spiral around the bar, as seen in the image.
Purpose of These Ribs:
1. Improved Bonding with Concrete
The ribs provide a mechanical interlock with the concrete, significantly enhancing the bond strength between the rebar and the concrete matrix.
2. Prevents Slippage
The ribs help prevent the bar from slipping inside the concrete under tensile or compressive loads.
3. Structural Integrity
This ensures the reinforced concrete acts as a composite material, allowing stresses to be transferred effectively between steel and concrete.