Rebar grades in Bangladesh: what 420, 500 and DWR mean
, 2 minute read, by Mashrur Corporation
Reinforcement steel is the largest single material cost in most concrete structures, and the grade printed on the bar decides how much of it the engineer needs. The names look like code, but each part of the name means something specific.
Reading the grade name
Bangladesh follows BDS ISO 6935-2 for ribbed reinforcing bars. In a name such as B500DWR, the number is the minimum yield strength in megapascals, so a 500 bar yields at 500 MPa or more. The letter after the number is the ductility class, W means weldable, and R means ribbed.
The three grades buyers meet most often are B420DWR, B500CWR and B500DWR. The older trade name 60 grade refers to a yield of about 420 MPa, and 40 grade to about 280 MPa. You will still hear both on site.
Why the ductility letter matters
Ductility is the bar's ability to stretch before it breaks. In an earthquake that stretch is what lets a frame bend and absorb energy without failing suddenly. Bangladesh sits in a seismically active region, which is why structural engineers here commonly specify the D class for beams and columns. Do not substitute a different class without the engineer's written agreement, even if the strength number is the same.
500 or 420
A higher grade can reduce the tonnage of steel in a design, but only if the structure was designed for it. Swapping 420 for 500, or the reverse, on site without redesign is not a like-for-like change. Buy what the structural drawing calls for.
What to check when the truck arrives
- The brand and grade rolled into the bar surface match the order.
- A mill test certificate comes with the lot and its heat number can be traced.
- Diameter and length are as ordered. Standard bars are usually 12 m long.
- Weight is settled on a weighbridge slip, or you have agreed in advance to bill by theoretical weight.
- Bars are free of heavy flaking rust, oil and mud. Light surface rust is normal.
A quick weight check
The weight of a steel bar in kilograms per metre is close to the diameter in millimetres squared, divided by 162. A 16 mm bar is therefore about 1.58 kg per metre, and a 12 m length about 19 kg. Counting bars and multiplying is a fast way to sense-check a delivery against the challan.
This is general guidance. Standards, duties and procurement rules change, so confirm current requirements for your project before acting on it.